I have an 89 k1500 with a 350 and a 5speed. 350 finally let a head gasket go and is toast. I would like to keep the tbi. I have a 283 I assembled with a stock 327 cam and a set of 305 HO heads milled down to 56cc. Flat top pistons, so calculated around 10:1. Long tube headers and dual 2.5 into single 3 inch glass pack muffler. Will I need custom tuning or should it run fine without it? Vacuum when ran on the test stand with a carburetor was around 20 inches. If I do need an eprom burned, who do you guys recommend?