Just to be aware, there might be a place on your block that is a remnant of when the engine used the small house shaped fuel pump. The fuel pump of years past.
The bosses and holes might already be there, you just gotta get the fuel pump, scrap the VRO, and start pre-mixing your gas.
If you end up being convinced by your mechanic that the VRO is bad (that sounds to me like what he is trying to do), then you can go back with a much cheaper fuel pump replacement.
That is, IF you have the mounting bosses and pulse source cast in the block. You will have to inspect to see.