when I dyno'd I had the stock injectors in place, with megasquirt I am running DSM 450cc's, as for max safe boost
I think the 10psi rule is due to the lean condition at top, when I dynod I had the base pressure way up with a rising rate FPR and still went lean and right about 10 psi it started to ping, once I got the MSnS I started turing up the boost and on a hot day at about 14 psi it pings so I backed it off a touch
The combustion chamber is a bad design but the Bosch L Jetronic is the bigger barrier in making power and running bigger boost levels, not only is peak so much better the better fuel/spark curve has really opened up midrange power, it's like driving a different car
and yeah I am quite happy with my 183k mile junkyard motor, I was worried and the car I got it out of was burried in the back of the junkyard for who knows how long I intend to build a replacement block before I upgrade turbo and shoot for 400whp but thats gonna be a while yet