IIRC,
Mike Kirby uses a 2.11 intake valve in a 3.901 bore,with his 12 port head.
The L-92 head has a 2.160" intake?
L-92 flow numbers. http://www.proheads.com/WCCH%20L-92.html
You could install smaller seats maybe in those heads?

All Pro heads flow up to 440 CFM! http://www.proheads.com/products.html


MBHD

12 port SDS EFI