[68ragtop]

I would snap up that 455. With machine work, pistons, bearings, Etc, Etc.
Its almost impossible to build a pontiac engine for $1000, let alone buy a 455 ready to go.

68RT

[goquick]

I would look at the Comp XE268 cam and matching kit with springs. 224/230 @ .050", .477"/.480" lift, 110lsa. Install it at 104 off the crank. Get larger 2.05 intake valves installed. A ford cleveland exhaust valve works well. Change to screw in rocker studs. Open up the pushrod bulge width to 1.050". Go to a hobby shop and get the .032" thick bronze tubes that will just clear the head bolt threads. Drill out the head bolt holes between the intake ports and install the tubes. Around here, shops charge 60 bucks for this. Now on the head bolt area in the port, open up the port until you just start to see the tubes just installed. Especially at the bottom of the port. Now get an old 1.66 ex. valve to use as a guide in the bowl. Open up the port throat under the intake valve until the 1.66" exhaust valve just slips in to the bottom of the valve guide. Fill exhaust crossover in the heads if possible with alum. Shops here charge 125 to do this. Use a 1 3/4" 4 tube headers. The 1 5/8" on the market now are not big enough unless you have a 301, which they won't fit anyway. These new smaller tubes are just cheaper to make for the header companies. Use a 2 1/2" exhaust system to either a set of Magnaflow or Dynomax ultraflows with 2 1/2" tailpipes. Put 3.42 or 3.55 rear gears in. Your performer intake is fine for this combo. Just port match it. Get the q-jet rebuilt by someone like Cliff or Carbking. A holley Street Advenger carb with the 770 cfm rating works well also. The 670 is a little small. This will be a good drivable desent powermaking combo.