I am thinking this is a 350-30 over Flat top piston short block . And I hope it has good rod bolts ? Now with your 342 gear thats ok for a street / strip build . And That 700R trans with it low first gear . This is what I think will work good . For the Camshaft the Comp Cams XE268H . It's 224/230 dur at 050 and 477/480 lift with a 110 L/S . Also use a Cloyes true roller timing set . For the Intake Manifold use the Weiand Stealth Air Strike #8502 Vortec . That 650Edelbrock carb will work good . But I think a 700 D/P Holley #4778C would be better . Also run a good HEI with a high volt coil . And some long tube 1' 5/8 headers . You should have 10.1 C/R with a 0.41 head gasket and flat tops . And your 355 should have 390 HP at 5800-RPM and 405 Torque at 3500-RPM . Put this engine together and you will have one fast Truck . COOL