Shafiroff Racing Engines is in the Northeast. They offer a rebuild and repair for complete engines.

Including a dyno test after the rebuild according to their website. They many be worth contacting or any of the multitude of LS1Tech sponsors. Thompson Motorsports or Texas Speed can probably do the same sort of thing.

Per Shafiroff Racing Engines website they typically include the following:

• Completely disassemble your engine and inspect each component for wear or damage
• Disassemble your cylinder heads and inspect for wear or damage
• Check valves, valve guides and seats
• Boil block, brush oil galleys and tap head bolt and main cap holes
• Paint outside of block with hi-temp paint
• Check rod and crank sizing, boil & polish crankshaft
• Install new cam bearings
• Hone block with torque plate
• Disassemble and inspect oil pump
• Assemble complete engine, check all bearing clearances and end play
• Includes new Total Seal 1/16 ringset, Clevite H Series bearings, FelPro head gaskets, timing cover, oil pan, valve cover gaskets and rear main seal
• Degree cam, check piston to valve clearance, verify top dead center and set pointer
• Assemble cylinder heads, check spring pressure, set spring heights and install new seals
• Break-in engine to seat rings and test power output and provide actual dyno sheet
• Check for leaks, verify proper oil pressure, check individual cylinder leakage and compression
• Cut oil filter open and inspect