I know the part numbers are different and I saw an old discussion stating they are in fact different, I was just curious if anyone knew what the actual differences where.

They are completely different, the 76a has much thinner valves that use shim adjustment and have one valve spring, the B4 has the old style nut and pin adjuster and two srings plus the cams on the 76a have larger dia journals.

Excellent info, just wanted to know. Time to order them up from Japan.