Big blocks weigh less than 6cyl generally. Why would a T5 have trouble with an engine 2 cubes less than a SBC 350? I put a 454 in a 56GMC, no problem. The 348 is a heavy engine but is about 5 lbs lighter than an old 235. The 348 is about the showyest engine in the world. Always wanted one or a 409. Get a universal crossmember and mock it in. Need to find what headers fit between frame and clear steering. Use universal cross member for the tranny. Recommend automatic. A whole lot less trouble/money and plenty fast. Use Lokar nostalgic shifter. The 348, being the first Chevy Big Block, had a funky block design for sure, "W" block, 74 deg deck angle, exhaust port spacing looks like a small block.
