I also have a Knudsen head for my 51 Biz Coupe. Mine was from a speed boat,and has the water tube mounted front and rear on the head.
Is yours like this?
I also managed to buy a Knudsen 3 x 1 intake.
Only took about 3 years to spot this stuff for sale,and a microsecond to hit the "buy it now" button. I would tell you what I paid,but it's too painful.
Sill looking for a set of cast iron headers.
