I would feel a lot more comfortable with a built 351W.
302 had about 150K miles with trickflow heads, cam and intake. My kids drove it and pushed it to the limit. Lower end of motor blew apart. Crank split in 2 and block had a crack in the lifter gallery above the cam which ran the length of the cam. This is how those blocks are known to fail. Not sure which went first the block or the crank.
Put 94 351W in from a truck with TF heads and a blower. Never put on Dyno but estimate around 500 HP. Supposedly 351W block stock rotating assembly good for at least 800HP. If you are going to adapt a blower or turbo would help if you had access to a machine shop unless you can find a direct bolt on assembly.
As noted above had to change oil pan, headers, flywheel, damper pulley, distributor and intake. Also need a taller hood to fit it in. Watch out for high volume aftermarket oil pan, it hit the steering rack so I had to put spacers between block and motor mounts. Polyurethane mounts sagged over time so I put in solid mounts.
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