Terry, that is correct, the LT1 f-bodys do take the PF25 as their stock filter, so I run the longer PF35/PF1218 substitutes myself. So if his LT-1 engine can take the PF25, he could use the same filters I use, so long as his ground clearance is ok. I believe you're right, the replacement for the PF25 is the new PF454 or something very close to that number.
FWIW, the long filters I have been running are around 5.2" long, while these longer racing filters I mentioned are around 8" long! Definitely a nice easy way to put an extra one quart of oil into your system. Plus the flow rating is amazing! (one of them is rated at 28GPM!!)