Lets do the math then, and see how it comes out on a T-70
compressor map, instead of ...... "well it should cause they run it on 302's and 289/4.6L's "
Thats great but he has a 347 ....... not a mild 302 or 4.6L mod-motor
347 X .5 X .8 X 6,000 / 1728 = apx 500 cfm N/A
11 + 14.7 / 14.7 = 1.75 PR
500 X 1.75 = apx 900cfm at 10 psi
900 X .076 = apx 69 lbs/min
Now lets plot 70 lbs/min and 1.8 PR
on compressor map of a T-70
As you can see at 10-11psi and the flow rate needed for a 347 at 6,000 rpm
the T-70 is way off its efficiency compressor map.
This will put alot of extra heat into the system and give issues.
The last line on a compressor map is known as "The Choke Line"
You want to avoid going past it at all cost if possible
Choke line: The maximum centrifugal compressor volume flow rate is normally limited by the cross-section at the compressor inlet. When the flow at the wheel inlet reaches sonic velocity, no further flow rate increase is possible. The choke line can be recognised by the steeply descending speed lines at the right on the compressor map
You guys need to watch the bad info you hand out, "just because
someone else did it on a totally different motor". They make those compressor maps FOR A REASON !!!
Here's some good reading on how to properly pick a turbo