bviller,
I was part owner of the BMW factory 320 IMSA turbo car for some time and when we went to sell it the buyer required that we run it on the dyno. We set it up and as I remember we did run the boost as high as 80 inches and we had somewhat of the same problem you had with the connector hoses blowing off and also splitting. To fix this we would use 3 clamps, one on each side of the tube bead and then one in the middle to keep the hose from bulging. We also used some .040 lock wire and lock wired all of them together! this stopped them from blowing apart. And it allowed us to really blow it up! A piston/rod assembly, a sleeve and some head repair got it up to around 650 hp. Not bad for 121 inches, mechanical fuel injection (Kugalfisher) and gas in 1987.
Rex