1965 273 Heads

Well said! the only place I've found Hp273 pistons listed is on Egge's
website. I would imagine thats where Laysons gets theirs. The HP273 is a
fun little motor but if you want to go fast build a bigger engine. Unless you need to keep your car 100% original you can build any small block you want
and put it in your car up to over 400 cubes. The HP is limited only to your pocketbook. I'm building a stock bore 318 with mildly ported Magnum heads
(9.0-1) Air gap intake etc. to replace the very tired HP 273 in my 66 Dart.
I may like the way it runs so well I'll just leave it in there and store the original. toolmanmike