Using an A/F meter on TurboStude per Darren Dawes:

Thank you for your interest in our products! Wow, it looks like you've
put a lot of work into your car! I should tell you that the original O2
sensor in this car is not the best unit to use. It relies on the manifold
for it's ground, which is notorious for causing signal loss. I'd suggest
one from a 91 Dodge Shadow, as they are pretty cheap at $45 and have a built
in heater. The threads should match, just bring the old one with you to the
parts store. To answer your question; you can get by with the standard 2.2
model, with a couple of caveats. First, let me point out that our extended
range model has it's color coding set up to show the "safe" zone to be .90
to .95 volts on the O2 sensor. If you are running more than 8:1 compression
with your anticipated 15 psi, then I would strongly suggest keeping the O2
reading in the .90-.95v range. The Dodge unit is color coded to show "safe"
as .87 to .90v, which may be a little lean for you. This is not a problem if
you want to use this meter, as it also has two more lights showing .90-.93v
and .93-1.1v(limit of O2 sensor). If you use the Dodge model, you'll just
want to keep the first green light lit up. These are general
recommendations based on what works in most applications. Without knowing
the compression and the cylinder head chamber characteristics, it's hard to
be more exact. However, these recommendations should keep you out of
trouble. Start off at very low boost with a ton of fuel, and tune from
there. Read your plugs (you don't want to see "salt and/or pepper" deposits)
and listen for detonation. You may also benefit from a little water
injection(not elegant, but effective). Go slowly, you are in uncharted
territory. Now that I've attempted to scare you, I'll wish you well with
your project. Let us know how it turns out!

Darren Dawes

--Dawes Devices