There may be headspace issues with this rifle, but the biggest problem with them was at the gas port. Bolts can be refitted (if you have the gauges and the inclination) but the gas-port problem needs some heavy thinking AND the right tool in order to do efficiently.
I have seen one of these rifles that literally self-destructed as a result of a "small problem" at the gas port. The problem is easily solved, as with any gas-operated rifle, but you have to know what you're doing.
I have written an article on gas problems (with specific reference to the 555, the FAL and the AG-42) and if anybody wants a copy, PM me with your REGULAR e-mail address: the article is too big to go through the cgn PM system.
I got the last Finnish SVT-40 that Globe had in Ottawa, still have it. It had a 555 magazine, which I would love to swap for a Tok magazine. The rifle is Finnish-marked, of course, 1940 mfg, serials are scrambled like an omelette, but it shoots very nicely. Sure wish I had got a 555 back when they were $149 at Al's Cycle Shop in Brandon. Oh, well......... can't have everything!