I'd keep the Y-Block also. SBF's are getting to be the new SBC, everybody's got one. Y-Blocks sound fantastic and a dress ones are one of the best looking engines around. depending on what kind of driving you do there is several transmissions to choose from.
Here's one of mine with a C-4
But keeping the Y or not wasn't the question. OP asked "Anyone know of an East Coast Y-Block builder?"