M62 on Isuzu diesel

Hi, I'm new to the site, and am currently putting a M62 Eaton on a 2.2 Isuzu diesel that I have installed in a 1928 Chevy coupe. I want just a little more grunt on hills, without redlining the engine- so I am looking at 5 psi boost. The drive ratio will be 1.5 to 1 speedup, max. engine revs 4300 (although I prefer not to turn it that fast), so blower revs will be 6K tops.

My question is- there are two 9/16" holes in the flat area of the blower bottom, near the drive end, and outside the discharge hole. NOT talking about the oval silencing ports.There are also two similar holes, 7/16" back near the boost relief butterfly valve. Front and rear holes on each side seem to be connected to an area between the inner and outer blower casings, and the rear holes extend upwards to the outside of the blower, with one being capped off with a plate stamped "EGR" It would make sense to me if somehow, cool air was circulated between the inner and outer blower casings, to remove heat, but with one (or possibly both-I dont know what was connected to the unplugged one) used for EGR, it seems that whatever was induced inbetween the housings was as hot, or hotter than the discharged air. I have no use for EGR- as far as I am concerned I block it off on any vehicle that I have-why pipe that crap in to dilute the mixture- S###W the EPA.

Can anyone shed any light on why there is a space between the inner and outer housings- and where the two forward holes discharge into (probably the compressed air portion of the manifold- I never saw the stock application manifold).

Thanks,

Gromit