engine 74gto

I have a 1974 gto with a 350cu.in. engine, 4 speed saginaw transmission. I would like to replace this engine with a bigger cu engine. What size engine can I replace the 350cu.in. with? I want a replacement with little
modification and that will match up with the 4 speed trans.
Thanks for your time

Pontiac 400 or 455 will bolt right up.

i have a 400 with cating #s 9790071 on rear of block and 611216wt on front with date code of d048 by the dist complete motor except carb have several that can go with dont know what they are off of though



robert l. zeigler