I recently faced the same issues with my '42 chev PU... I put a rebuilt .030 over '60 235 in mine mated to an S10 5-speed tranny through open drive. I also put in a rear with 3.55 ratio from a '70 Nova. That 270 you have sounds like a great choice for resto...I kept my stock frame... but put on power front discs.
As far as the MII IFS the previous thread on this issue is not totally correct...MII IFS front end's are only lowered if you use "dropped" spindles, most vendors offer stock height spindles which maintains the stock height. Good luck
