I bought these 289 Hi-Performance (Hi-Po) K-Code heads to replace the regular heads that came on the car. 
I sent out the engine to be machined (Magnafluxed & hot tanked) to Roberts Machine Shop in Lexington, Kentucky.
He does great work at a fair price. He honed the cylinders, put in new rings, and new crankshaft bearings. 
He replaced the valves and springs, then he pressure checked and set them to 19 lbs pressure. 
I still have the original heads and exhaust manifolds that came with the car. If you're not sure which heads that you have, 
look above the 289 on the heads, a single dot above the "289" means regular, two dots means hi-performance heads.
469 Curry Ave (859) 389-9201 Lexington KY 40508
Lexington Automotive Machine, Servicing Lexington, Fayette County and Surrounding Areas