I had a 90 454SS here with a blown 350 someone put in it...had 2 thrown rods..700R4 ..I bought it..pulled the 350 700r out...put a 454 th400 back in out of a 90 ton.. I then kept the 454SS 14bolt 5lug rear,put a 10 bolt rear in it...off to the auction it went and i trippled my money in the rust bucket..
It was just to make money on..but i cant keep them all...you know..
The stock 350 motor mounts on those are the same as 454 mounts..will bolt right up
you will have to lose the stock V6 motor stands..and bolt the mounts to the frame..
But its not to bad to do...headers are pricey..yes but stock 454 truck manifolds work good too...
Up grade your trans for sure..while your in there..