No I haven't checked, but I am running a 140amp alternator and at idle rpm with my two electric fuel pumps, electric crank case vacuum pump and the radiator fan going the voltage was over 12.5v, and goes up from there with rpm.
With the small cam advanced around 2* (due to the thicker head gasket), it was pulling to 5,800rpm, and seemed to peak about 5,300rpm. General consensus is the engine/head/cam should peak around 5,400rpm. With the cam timing fiddling, my goal is to get it to peak around 5,500rpm, and with the porting and valve springs, try and get it to pull to 6,000rpm. Factory redline was 6,500rpm, but again, general consensus is the engines, from the factory, rarely did well past 5,400-5,500rpm. I want to keep it advanced enough that I make up for lower compression than a 4bbl Sprint head (by closing the intake valve sooner), but at the same time I don't kill off the top end rpms entirely.
In this configuration I'd like to at least rev to 5,400rpm, but will only have to live with it another week before I take it all apart, port the head and shave a few hundredths off the head to gain some compression back. Then perhaps I won't need to advance the cam to up my dynamic compression and will be able to better cater to the upper rpm's.
Rebuilding an OHC Pontiac 250 with EFI and a Turbo