L32 will work, but it will be a lot more expensive than using L67 stuff, just because it will be low milage. The L32 heads do have bigger vavles and with the added efficeny of the Gen V yes you will make more power pulley for pulley. You'll also "have" to run a 75mm TB because that's what coems stock on the L32's.
I've had a supercharged L36. For all the work it took me I really would have rather had gone to a non-intercooled Turbo kit with meth injection. And keep around 10psi. That would be enough for a low 13's pass if you can launch it well enough. By the time you buy heads/Gen V/TB/Intercooler/Head Studs/headers/gaskets the Top swap will probably be about the same cost as a turbo kit. With less room to advance. The Turbo's also going to be a much easier install !
I've seen turbo cars consistently get better gas milage up here, but that just might be a tuning difference between our two main tuners.
Just an FYI, my SSM90 (S/C kit from ZZP) WIth PEMs/SLP 1.8RR/3" DP/Catback and a 3.5 pulley I went 13.5@98.88 with a 1.9 60' . Stock GT Throttle body, a few degress of KR. So it works, but I really had no where to go without headers/cam etc... I sold the kit and was going to go turbo, but instead sold the car and built a motor for another GP and then it blew up

I like the turbo option, with the twist of a wrist you can detrime how much power you want.