I don't know much about this motor, but I might be inclined to stay away from the Ramjets.
I'm probably in the minority, but as I recall, these were designed as boat motors, not for vehicles.
the little I remember about the ramjet 350 was there was no O2 sensor, and there may not be a knock sensor. If both of those are "missing", that tells me that there is probably a BIG compromise in performance because GM had to keep the engine "safe", likely with lower compression and a fairly mild timing curve. With aluminum heads the compression is probably 9:1 (total guess here, tell me if I'm right or wrong) but that is still real mild when you can run 9:1+ easily on iron heads with 87 octane.
Probably has a decent warranty, but do some more research, see if you can't find a 502 with a better injection system on it already, such as Edelbrock, etc. (not saying yay or nay on Edelbrock, but their injection systems seem to work fairly well)
Someone is probably offering a more "tuneable" injection setup pre-packaged with a new 502. As much as the ramjet costs, I'm sure there are similar out there.
A little out of the purview of your question, but last I knew, a major pitfall on these IS the fact that they aren't a very "smart" fuel injection setup.