318 wont rev above 5,300

Looks to me your cam is tapped out!! These are the specs below that I googled,

Basic Operating RPM Range 1,800-5,500
Intake Duration at 050 inch Lift 218
Exhaust Duration at 050 inch Lift 228
Duration at 050 inch Lift 218 int./228 exh.
Advertised Intake Duration 276
Advertised Exhaust Duration 286
Advertised Duration 276 int./286 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.441 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.441 in.
Valve Lift with Factory Rocker Arm Ratio 0.441 int./0.441 exh.
Lobe Separation (degrees) 114
Computer-Controlled Compatible No
Valve Springs Required Yes
Camshaft Manufacturers Description Fair-smooth idle, low-midrange power. Works with stock-2,000 stall, 9:1


I would suggest to get that 3.91 out of it and install a 2.91 or a 3.23. Turbo's like "load"....Bet with this gear change you could see high 10's low 11's!!