Beautiful bike. Chroming was much more popular in the '70s and '80s but due to ti being rather toxic it fell out of favor.
I wouldn't get too hung up on the exact model since you bought it as a frame only and built it up. I am not sure but '85 might be a tad early for SLX.
The value is going to be up to a potential buyer. Someone who just wants a good quality chrome Italian bike to ride might pay several hundred dollars for it but I don't think you'll see values like a DeRosa or Colnago might see.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk