Yes you can put a Chevy in a Pontiac. The GTO is the same body as the Chevelle, so you just need Chevelle motor mounts, either an adaptor for the trans, or just get a Chevy trans,(they're the same except for the bellhousing bolt pattern)
Reroute some fuel lines, starter wires, some other odd stuff and you're there.
The Pontiac engine is better for the street, though.
If you want a big block racing engine, Chevy is the way to go.
These guys are the best
Here you go:
"Reher-Morrison puts the latest race winning technology into a Sportsman engine that is perfect for Quick 8, Quick 16, Top Dragster or Top Sportsman! The newest Reher-Morrison Super Series engine is the Super Series 622. Reher-Morrison's continuing R&D has produced a new Super Series engine that makes 1280 HP and 950 ft./lbs. of Torque!
If you are looking to be the quickest, fastest, and the most consistent, the new Reher-Morrison Super Series 622 is for you! From Reher-Morrison "Your Engine & Parts Department!"
? Block - Dart Big 'M' Tall Deck Block
? Carburetor - Gary Williams flow matched 1150 Dominator Carbs
? Intake Manifold - RFE Spreadport Intake
? Valve Covers - RMRE Billet Rail Sheetmetal Valve Covers
? Cylinder Heads - RMRE/Dart 14° Big Chief CNC Oval Port Heads
? Valve Springs - Comp Cams Triple Valve Springs
? Retainers - 10° Titanium Retainers
? Rocker Arms -Shaft Mounted Rocker Arms
? Pushrods - IRC tapered pushrods
? Lifters - Crower Cutaway Roller Lifters
? Camshaft - Reher-Morrison Custom Ground 7/4 Firing Order Swap Camshaft
? Pistons - Reher-Morrison Gas Ported 4.625" Custom Pistons
? Piston Rings - RMRE/Total Seal Rings, .043BC/ .043 / 3/16
? Rods - C&A 6.750" Speedway Rods
? Crank - Callies 4340 4.625" Stroke
? Timing System - Jesel Belt Drive
? Crank Trigger - Mallory Crank Trigger Kit & Distributor
? Plug Wires - RMRE/Moroso Custom Spark Plug Wires
? Oil System - Reher-Morrison Dry Sump Kit
? Vacuum Pump - Reher-Morrison Vacuum Pump Kit
? Damper - ATI Damper, SFI Approved
? Head Studs - Dart Head Stud Kit "