Engine Block Cracked

[Alien]

Isn’t the LT1 the same bellhousing bolt pattern and depths as every other SBC? I’ve been running the old 305TPI with T5. From what I read I thought the LT1 bolts right up bellhousing flywheel clutch and all. I may have misunderstood something here. I guess I need to do some more digging. I got Time. I’ll do some more research.

Your 305 is a 1pc rear main, correct? I can't remember if all TPI's were the later style.
Yes, the T5 bellhousing bolts right up to the LT1, and the T56 bellhousing will bolt up to the 305.
Canton pan fits both 305 and LT1

I've run my (world class) T5 for a few years behind the 305. I did go through it and did some of the standard upgrades (bearing retainer I think?) quite a few years ago when I dropped in the LT1. A lot will depend how you drive it to make it survive. No sidestepping the clutch on the standing starts, don't just slam your shifts.

I'm using the T5 clutch and hydraulics. I took the flywheel to get balance matched to the LT1 flywheel, just to be sure. Don't remember what they did, but that particular flywheel was on a few previous engines.

5.3L is nice and if something major happens I'll go that route. As mentioned, the longblock is the cheap and easy part. It's all the other stuff that adds up. Exhaust and intake manifolds if you don't have them, custom y-pipe, engine crossmember notched (sometimes), trans crossmember (Holley is great, but interferes with my Alston subframes), accessories, oil pan and Improved trap door for oil control, hoses, wiring...