275 hp reliable?

The /6 already has decent torque related to it’s c.i. displacement. If you’re planning on ending up with a supercharged engine anyway, You might as well do the engine upgrades first.
Some easy and relatively cheap mods would be to get a better intake (2 bbl. or 4 bbl.) And a good header/exhaust system. Next you may want to have the head shaved and ported to raise the compression ratio and breathe better, along with a better cam. You should already have a double row timing chain, so while you’re doing the head work and cam, replace that and the gears too.
These mods alone should significantly wake up your slant, and you can be driving it while you upgrade without months of downtime, since you don’t have to do it all at once like a supercharger.
I would think for a first time driver this would be plenty of performance.