[olblue81]

You can use the block as a starting point for a performance motor but to take an existing working engine and try to make some power out of it by bolting parts on will be disappointing.

They have a bulletproof bottom end, but the pistons are heavy because of 1 extra ring at the top. The heads are "peanut port" and are very low flowing and the intakes are cast iron with dual thermostats-heavy and hot. You can swap out the heads to something better flowing and change the intake to a short deck unit by using adapter plates but the compression ratio will still be low due to the large piston to deck clearance. Because of the higher deck height you will need to use a tall deck distributor.

It's been 20 years since I rebuilt one, but if I remember correctly the factory compression ratio was in the low 7s or high 6s.

Do some math on it and price out the parts you need to put a decent top end on the motor keeping in mind that no matter what head you put on it you'll probably still have a low compression motor. If you can buy the complete motor cheap enough, then go for it. It's better than a 305, but unless you were going for a complete rebuild from the bottom up you can end up with more money tied up in it than a 454 and make less power.