slant fuel injection opinions

ok, I have been mulling over fuel injecting my slant. fighting this 450 Holley is pushing my limits. just want to enjoy the car. ( I did add a wideband to try helping, just need to wire it up)
looking at the FiTech ( with the power adder option for later ) have considered getting a rail and set of bungs to add multiport ( maybe mega squirt ).
the car is a 1966 Valiant with a warmed up 225 ( ported head, bigger valves, cam, hurricane intake, Clifford headers ) with a 904 and a nice stall.
I have messed with Holley's for years never had one fight me drivability wise like this one.
my guess its related to the carb being somewhat oversized for its use. ideally I would have run a 350 2 barrel but, had the intake and carb already.