I can see an LS1 weighing in as the same as a 13b-rew or a 13bt but not a 12a. Just be careful when sourcing a 13b I keep seeing ones on eBay and some of the import sites that are out of forklifts. They are awesome cars and while they can be a pain the ass sometimes they are am absolute joy to own. The best advice I can give you is make sure your battery is always strong, if not you are up Shits creek. I keeps seeing RX7 and it makes me miss my old turbo FC...