The high 4's sounds about right with the rev limiter at stock setting, I believe it's 4800 if memory serves, just that with the 308's your usually doing around 95 or so. I can't comment on the tranny work you have done but my ride with the Apten chip and Jmod for under 350 hp will hold shift points up to 5500 rpm, probably further but I haven't had the nerve to stay on it that long. You already did the rear end. I would say your money is going to best spent upgrading the torque converter/flex plate and kick the stock air box, upgrade the maf and get the chip. Oh yea, I would spend the money on the drive shaft first, that vibration would drive me nuts.
98 4.6 SOHC, J-Modded, B & M 24K Tranny Cooler, Cold Air Intake, 76 MM MAF, RM Tube, March 1150 U/D Pullies, Poly Bushings, Air Bags, MK VIII Brakes and Wheels, Trak-Lok w/ 3.55's MK VIII Flex plate and Marauder T/C. Now that it can go, it'll be time for show.