225 High Performance Engine / 904 Trans / 2 1/2 Inch Pypes exhaust - What Is It Worth

oh that was certainly taken into consideration. i know what machine work costs and it's not cheap. however, if you're selling something used like a motor or transmission labor actions such as that are sunk costs. "rebuilt" will add to the appeal and may bump the price up but you're not getting full book back on stuff like that.

the intake and exhaust are the real diamond in the goat's *** here and people are still having a hard time moving complete /6 setups.

if i was in the market or knew one of my clients would want something like this down the line i'd probably jump on it. but at that price point it's too much of a gamble for not enough ROI. but if you had a roller and wanted a hot slant setup this would be the jam and one hell of a deal.
You are looking at this in a different light. You would want yo flip it for profit, thus looking to lowball the seller. You know what the cost would be to duplicate this assembly. Machine shop time, new engine parts and assembly. From the dedcription the trans is in working order as it seems to be driving at the time of removal to install a 340. Then the intake, carb and complete exhaust. I think $5000 would not do the build. Seller is looking for a fair price recommendation.
To the OP, check into what the machining costs would be, with new overhaul parts. What was done to the head, ground valves and seats or new valves, guides and seats? Then research the replacrment costs for the intake, carb and exhaust manifolds. Then there would be the cost to do the dual to single 2 1/2" exhaust. And the transmission cost for a rebuilt. Might need to be patient to find a person considering doing a build like this for themself. Being almost broken in, I would consider starting at 75% of the cost to replicate what you have. This gives a little room to come down a bit. Do not let the lowballers and part it out contingent brow beat you. For the right person they will get a running engine to drop in with minimal time involved. You get a reasonable price for what you have.