My old '73 re-ring 440 combination (pretty much the same except 484 instead of 474) ran it's best ET with a 9" converter and 4000-ish stall.

Just trying to say personally I think it will be fine, no worries.

I can't tell you what hp you will achieve if you do or don't do some work to the heads, but I can say it would be a worthwhile test to run it both ways.

There has never been a more perfect application for P4286754 head gaskets. I hope you can use them.