Small roots blower for smallblock

Just from experience.
I have a 9:1 SBC with a 144, basically stock vette 79 L82 motor with true duels.
The more restriction your heads and exhaust are the more boost you will make.
Mine averages about 4 psi this is with a stock 114 degree cam.

Your basically stock 2bbl 273 is a good candidate for the 144 as long as you make some changes.
Good exhaust.
Fuel pump a carter super street mechanical with a holley regulator.
Limit your total advance on the distributor to around 28 degrees, but put as much inital as you can, like 16-20 degrees.
Put an adjustable vacuum advance can on it and turn it down to around 9 in.
3310 holley would work good, boost reference it with 2 jets larger to start out with.
This would be a starting point.
Add a AFM to dial it in, do not let it detonate or go lean it will come apart if you do.