Unless the car has been horribly neglected, you shouldn't have a sludge issue. A valve cover gasket & 4 spark plug tube seals will only set you back $20-$25 bucks, and since it's due a valve adjustment anyway, why not pop the cover off & look at it? The ARX is a good idea, just to free up the ring packs. As for oil, I agree with some other posts, this car is so easy on oil, a high quality dino like Havoline works great and easily does 5K intervals with positive analysis results, in most circumstances.
The more pressing thing to me would be the timing belt issue - do you happen to know for sure the belt has or has not been changed? The interval for these cars is 105K, so you're there.
Dealers in this area charge about $450 to $475 for that service which includes both timing belts, water pump replacement, both drive belts, cooling system flush, valve adjustment, and crank & camshaft oil seals. If you can do the job yourself, those parts will run you about $175 or so if you buy genuine Honda parts wholesale.
This vintage Honda engine is an interference engine, so not wise to gamble on if the belt has / has not been changed. If in doubt, you'd best belly-up to the bar and pay to have it done.
You've got a great car that will easily double the current mileage with very minimal care & maintenance.
Good luck w/ the car. Both of my daughter's have Accords & I enjoy working on them.
