Yes Pat the 80's Corvette only L98 Aluminum G.M Heads and TPI Manifold are the 1986 and Early Bolt angle . But I am sure you know about the 1987 and Newer F-Body / Passenger Car and Truck Cylinder Head and Manifold Bolt angle .

As for Valve springs I know the ones you use . I bought a set from you they are 125-130 Lbs at 1.700 install . He's talking about Iron Eagle Heads with what he calls Huge Springs . And with out known the part# of them Dart Heads it's anyone's Guess on a 1988 F-Body TPI intake bolting right on . But if you go ahead and just bolt on them Dart Heads with them Huge Springs may as well put Matching Huge 7/16" Screw in Studs Guide Plates Heavy Wall Hardened Pushrods Billet Steel Timing set and all the rest of that over kill of a Valve Train that you don't need for a Mild street Engine . Then why run Hydraulic Roller Lifters when Mechanical ones will give you more H.P power ?

Then after you get Done Bolting on all them High End Parts and Running all the Valves . Then see how that 1988 F-Body TPI Intake Bolt up . After spending all that Money and still going up Hill all the way on this Build . Just Google SB Chevy Tango and I will be more then Happy to help you Build it Right the 2nd Time for Less -> Roller or Flat Tappet COOL