Both BOVs should work. I think that quite a few of us have used the bosch one from the porsche so it's been a bit more "tested" so to speak. With either, you will either need to recirculate or put a one way check valve so it does not leak at idle and cause idle issues. I believe that there is a thread in the archives about adding a one way check valve from Lowes/HD to the Bosche to run VTA.
As for the engine management stuff, there are two separate issues to address. One is timing control and the other is fuel control. Since the SAFC-II only does fueling control (I think it may have a knock sensor feature, but does not control timing at least from what the APEXi website says, if it does then I apologize as I am not familiar with this piece) this will not work as a complete solution for higher boost.
For timing you have a few options: (there is an older JR unit that isn't common anymore so I won't mention that one)
1) 6-ish psi, you can retard your base timing to 6 and use the highest octane gas you have. Depending upon location/environment (aka only 91 octane, hot as crap, etc...), this may not be enough.
2) bipes (which is only a timing control unit so you'll need other stuff for fuel control)
3) e-manage (which does timing and fuel)
4) aftermarket ecu (aka link/haltech/etc....which does timing, fuel, and usually other stuff too)
For fueling again, several options: (all depends upon final desired power levels and of course depending upon which route, you'll probably get at least 1.8 injectors if not bigger)
1) AFPR/higher pressure fuel pump (this is what Begi uses for their base kit, can't fine tune as well as other options)
2) SAFC II (which only does fueling and not timing)
4) aftermarket ECU
5) RX-7 AFM/bigger injectors (has been reportedly done by one person, but you'd probably still need something for timing control)
While the prices of things can vary greatly (i.e. new/used/friend who has an extra for free), as a sweeping generalization, I'd leave you with two example setups:
If you plan to stay at 8psi or below, the cheapest
route (note: I didn't say best) would probably be to get a higher pressure FP (assuming your stock FP is not up to snuff ~$90), change the disc in your vortech (~$40), and get a used bipes (~$150) = ~$280 Biggest con is that you'd have to setup pretty rich for safety and don't have much fine control. Going above 8psi would mean bigger injectors, keep the HP FP/vortech, and add some better fueling control such as SAFC II, emanage, aftermarket ECU.
If you plan on going for bigger boost (aka 8+psi) in the long run, you will still need a bigger FP, bigger injectors, and can either get rid of or keep your current vortech (depending upon what size injectors you run). At this point, you could
still run a AFPR + bigger FP setup but you start tempting fate unless you like running pig rich all the time. Usually, this is the point that people go with something more robust like emanage/aftermarket ECU.
Again, if I was wrong about the SAFC-II being able to control timing as well then, I say go for it and be a pioneer to tune up yet another option for GReddy folk and be different in the process!
FWIW, I started with the base GReddy kit and went to 10psi with a used bipes $150, used BEGI AFPR $100, sold my Vortech on ebay for $90, 1.8 injectors or $40, and traded my stock exhaust for a used Pierburg. Like a lot of us, I didn't have a ton of cash to blow on electronics. BUT, to make a long story short, I've since switched to an emanage setup and #1 Wished I went emanage from the beginning since the difference between the two were night and day in my experience. YMMV. #2 Am now wishing for a complete aftermarket ECU setup for even more control/safety....it never ends....