I did see lots of bad ex valves and seats so that's a good possibility.

The ones from oddessa are chinese junk, crappy machine work crappy casting quality actually flow less than a stock head and will exadurate the problem of the fuel stream hitting the port wall at the pushrod because the pushrod pinch is much narrower than stock.

The second one is a rebuilt stock head but I would ask for better pics, looks like they sandblasted the entire assembled heads, valve tips, springs and all. Either that or something funky in the pictures.