B.B to 518 / S.B trans

What personal experience have you had when converting a 440 to adapt to a 518 or S. B t/f trans.
JW make the ultra bell, and I have seen other company's that have adaptor plates to make fit. Is 1 product better then the other?
I like the sound of adaptor plate as this doesn't limit me in fitting a 904 in future ( I am assuming adaptor allows this being S. B) Were the Ultrabell won't bolt up to the 904 pump.

If ultra bell is stronger and reliable it will be my choice.

I need the above for 2 applicatons I am working on. 440/ 800hp & 440/ 550 hp