I have moved in the direction of the W2 setup, as such I no longer need these heads. This listing highlights all the details of these heads, including the machine shop as well as the porting work I had done on them. Shown are the details of the parts: part numbers, costs, etc. Keep in mind, these are factory castings, as such of great value to those who want to run stuff like it. If you were to start with old factory castings today and needed to put the money into reconditioning them for performance use...well, don't go there, it makes no sense as you can buy aftermarket heads that put you well ahead in the "bang for the buck" game! Having said that, I had spent a good chunk of coin on these heads having started that work some 20 yrs ago (when aftermarket choices were pretty thin). Once the car was assembled I put on about 8 seasons of summer only driving for a total of about 7K miles. Please make note of the requirement to run epoxy in the exhaust cross-over port (explained at the end of the post). 1) '596 castings, which have had the 11/32 bronze guide liners installed, guides cut for PC valve seals, an original exhaust seat crack was repaired, combustion chambers are 61.5 cc and mirror polish finished, intake runner volume is 178 cc, the intake side has been cut to maintain the proper geometry 2) heads have been heavily ported, see photos below, here are the flow bench numbers (original numbers done on SF-600 at 25", converted to the 28" numbers you see below): LIFT I @ 28" E @ 28" E to I % Flow 0.100 67 57 86 0.150 102 79 78 0.200 138 104 76 0.250 175 125 71 0.300 205 140 68 0.350 232 152 65 0.400 253 160 63 0.450 267 167 62 0.500 282 172 61 0.550 291 175 60 0.600 283 177 63 3) parts 11826 Manley Severe duty valves, 11/32 stem, $130 11749 Manley Severe duty valves, 11/32 stem, $130 611-16 Comp Cams valve locks, $35 740-16 Comp Cams valve spring retainers, $90 1129 Hughes Engines dual valve springs, $150 (Hughes Engines) NOTE: Exhaust cross-over epoxy...the heads ended up having a porous casting (that's how the machine shop explained it to me) which causes a tiny little leak out from the cooling system. This happened after the 1st season I had them on, I suspect maybe the porting somehow weakened the structure, or maybe there simply was a flaw in the casting...not sure, I never ported the exhaust cross-over anyway since that made no sense. The shop filled the port with high-temperature epoxy which lasted three seasons until I pulled the heads to do some additional porting and machining of the deck. I had the shop re-do the epoxy work at that time since I had these out and the cost was only $100 to do so. If I was to put these back on I would certainly re-do the epoxy this time as well as it has been about three seasons since that was done last time. Alright...so what am I looking to do here? Make me an offer if you want these heads, I have absolutely no idea what heavily worked factory iron would be worth today (if anything??? LOL) . They are in great shape, literally a matter of getting the epoxy replaced and clean-up only...and you're back in the game. I have a pile more photos, if you want all these details email me please. Oh, shipping...grrh...I honestly cannot imagine this is worth it...too darn heavy and expensive. So for this one I would have to say local pickup only!