LT1 Head Question?
 

What is the best LT1 casting number? I'm looking for a good used set but want to make sure I get a good cast number for a engine project to come in the next year.

Thanks:)

The best for porting? Or just a good all around head.

643 or 374 for porting.

I'm looking to port and polish them. What years do these cast numbers come on?

For practical purposes they are the same. I wouldn't be too concerned about which specific casting number unless it's going to be a real wild port job. If it's not DIY, ask the person who is doing the porting if they have a preference.

Rich

There is a really good shop in my local area but they have never worked on a LT1. They have a flow bench and a engine dyno and I've seen some wicked engines out of this shop. They say bring them a set and they will make them flow. I just want to give them a good set.

I agree those are the best choices for porting.