I owned one of those for 20+ years, twin SU carbs, giant A/C compressor & all. Finally removed the compressor & under-dash AC.
*Oil: Though I always ran 20w50- either Valvoline or Castrol- for one that low mileage(90-odd thousand miles is barely broken in), I'd start with a good 15w40 HD oil. I would *Not* recommend an extended oil change interval on these cars, start at about 3000-3500 miles, & then if you really want to, begin working your way up.
*SU Carburetors: For the reservoirs on the SU carbs, use ATF, type A, Dexron, etc. Do *NOT* use motor oil like the owner's manual recommends. That tip came straight from the shop manager of the OKC Volvo dealership almost 40 years ago! You might also consider putting oiled foam sleeves on those air filters. Keep an eye on the fuel filter too- I finally wound up putting 2 inline filters in mine. I eventually changed out the SU for an aftermarket manifold with a single 2-bbl, 2 stage Weber carb(32/36?)
*Valve cover/spares etc: Don't put a Samson on the valve cover screws, the cover is easily deformed & will then leak. Keep a spare valve cover gasket or two, plus a stock of copper washers for the oil drain plug. BTW, you can use a copper washer twice if you turn it over afte the first use. You can *not* use it a third dime, unless you want an oil leak.
*Tires: Stick with normal sized tires(the old 165-15, or as close as you can get to it) & it'll feel more lively & steer better & your steering parts will last a *Long* time.
*Shocks: KYB Gas-A-Just shocks really transformed the feel of mine, & I recommend then highly. That's the Gas-A-Just, *NOT* the wimpy GR2's. If you can stand the extra $$ Bilsteins would be nice I'm sure.
*Valves: the B-18 requires periodic valve lash adjustment. If this procedure is in your skill set, great! If not, you'll need to learn. If you've never done it at all, let me know & I'll walk you through it. Tools needed are simple- a boxed/end wrench, screwdriver, & feeler gauges.
*Ignition: It'll have a Bosch ignition system. I recognize that coil mount in your engine bay! Back when I had mine, virtually all parts store manuals recommended the wrong points for my car. My distributor was centrifugal-advance only, all parts books back then claimed vacuum-advance. The points are different, so find out which you have & then keep at least 1 new set of points- and their corresponding capacitor(condenser)- on hand for spares. I'd recommend you keep a spare Distributor cap & rotor too. Nippon-Denso or NGK copper core plugs will run best. In my Volvo, Champions were fair at best, & Bosch plugs were nothing but trouble. Strange but true. Remember to keep the distributor lubed!
*Drive shaft: Mine had the 2-piece, 3-U-joint drive shaft. Whatever variation yours has, be sure to keep those U-Joints lubed. You may need a new protective rubber accordion boot for the center slip joint. And since you probably don't know when or if the slip joint(s)were lubed, Grease 'Em! Use a good grease & the slip joints will be good for another 100,000 miles or so.
*Rear Hubs: Volvo used several rear hub setups on those cars. One was just like a chevy, slip the holes in the brake drum over the lug studs. And then there was mine that required a special funky long-arm puller to remove the brake drums(some early 1950's Dodges/Plymouths had the same type, tapered axle shaft end with keyway into female counterpart on hub). After looking for years I finally found a suitable puller from good ol' J.C. Whitney. With the Internet these days, if you need one it should be fairly easy to find one.
*Work Manuals: Both AutoBook & Haynes are worth having. I let mine go with the car when I sold it in 1997. One is better at some things, the other better at others. You might even fine how-to videos on Youtube!
*****
I almost forgot:
*****Timing Gear!!! Keep your ignition, carbs and *Especially* manual choke cable properly adjusted for smooth running when it starts. Otherwise, on some cold morning, it'll cough. kick, & maybe backfire- and a stripped timing gear is the likely result! The crankshaft gear is steel, the timing gear teeth are fiber, and one good kickback can-and will often- strip them. If you can ever find a replacement that has tougher teeth, that would be a great preventive measure to take. Repeat: Don't let it backfire. No Foolin'.
Your new ancient Volvo is a beautiful example. I wish you all the best with it!
*The number one question people used to ask me: "Is that Columbo's car?"