so it could be the LA roller 360, which IMO is better than a magnum because you can use the far superior LA heads with shaft mount rockers and better flowing intake ports, that with porting have an average of 70+ cfm increase for around a 550 hp potential, Because the block has the oil feed hole to the heads
magnum heads full ported are done at 250 cfm, and thats max ported by a pro porter.
in ported form, the exhaust flows no more than an LA head.
just throwing it out there.