Ryan,

that depends on how much vibration you like!

I'd use a glass filled mount (e.g., DBr or GP) rather than an alum one. You can then back the mount with a thin piece of rubber (~1/16") all around it. The DBr mounts are circular so you just cut a ring.

Also, MK used to make some nice soft mounts for the YS's. Both the 45's and 61's fit in them. Basically there is a rubber dampener that mounts to hardwood beams for the engine and then, in turn, that is mounted between two steel plates that have screws passing through the assembly (see pics).

In a pinch, you can simply mount it directly with 4 x 6-32 bolts to the FW using the above glass mounts.

David.

P.S. Nice T2A! (small photo attached from Dan's brochure)