The 454 MAG EFI is a Great engine. I had one for 13 years and 1300 hours in a 200 Baja 272 with no major issues. I rebuilt it at 900 hrs when the engine was out for a new coupler, but it didn’t really need it and would have been fine with only a top end refresh. The crank, rods and pistons were near perfect. I always used Mercury oil with regular service. Ran great when I sold it. Good luck with your search.

Im very curious on the VST engines. I have read alot where they vapor lock. I have a VST 454 mag mpi soon to be 502 but the hours I used it I didnt have any problems vapor locking. i live in the south where the heat and humidity can get high. As i read above i guess the fix is running a return line but from where to where?