Those reliefs look pretty typical to me for a B1 head. Part of your issue is going to be the smaller bore which will cause those reliefs to take up a lot of real estate. I don't think if you ask Scott he would say that small bore is ideal for those heads by any means. What compression ratio are you shooting for. Typically you should end up with a net zero piston or close once the reliefs are countered by a small dome to get a typical "race engine" compression, for me that mean 15ish to 1 fwiw. I have done some 12/13-1 stuff like my Valiant was, piston looked pretty much like yours do, valve reliefs around 13-18 and flat top. You will end up with somewhere around that 13-18cc relief and be 12/13ish to 1 depending on how small the chamber is. I don't have those pics handy. Also did a B1 original that came in at 14-1, again sorry no pics. But similar to yours with a -10.45 CC piston in a 4.500" bore and a 63.1cc chamber with a .043"

Most my pictures these days are on photobucket and lost to me forever but have a couple on my phone.

This is a CP piston for 15-1 B1 deal. It is at +.8 CC's figuring relief and dome. 63.3cc chamber and a .038" gasket.



Next is a similar piston from Diamond again 15.2-1 bit larger chamber as they had been softened 84cc. Again though similar net CC's