Took my '55 88 Holiday in for head gaskets. Mechanic says the engine needs to be rebuilt. Should I rebuild the original 324 or go with another option? Would love to stay "Rocket".

 

Was the power adequate? You could bump compression and the cam size somewhat, depending on what manners you want. There are some differences between the size and years of the original Rocket V8. You know the original engine will fit along with all accessories.

 

Why does it need to be rebuilt? I would keep it original.

 

If you're going to re-build it, bore it out to 4 in. and use 1957 371 pistons.
It will make it a 346 and should give that '55 all the power it needs.

 

Where are you located ?
What made you decide the engine needed head gaskets ?

 

Make sure you get a compression test done before deciding to rebuild the engine. Better yet, a cylinder leak down test will tell you exactly what the engine is doing. You can rent a compression gauge from your local auto parts store (and maybe even a leak down tester) if you want to do the work yourself.

 

Curious, is a 371 crank fit a drop in along with the 4" bore to make a 371?

 

No. the block deck height was raised in 1957 for the 371.
But the pin to crown height remained the same.
Olds cylinder walls are very thick and can be bored out a lot.
22 cubic inches and about a point more compression plus a cam. Will make that 324 snarl.