If you intend to match the MAF to the 01 and newer intake then I would go with a 85 mm stock 01 and newer 85 mm (850 CFM) MAF rather then the '99s 75 mm (750 CFM) MAF.

If so then to really make it work well go with a newer PCM flash since its operating software and calibration was designed for the 85 mm where a '99 is not
Of course if using a newer MY flash and if your using a single user version of LS1edit then you'd have to buy another license to use on that newer flash which is not a issue for those of us with unlimited LS1edit.

If you do not go with newer flash then stay with the 75 mm.