Well, for comparison, I bought my '77 FJ40 in 2005 for $3500. On the plus side compared with yours, it has a 2F, 4spd, and front discs. On the minus side, it's not quite as original as yours, was missing a lot of small items, has cut/trimmed sheet metal and replacement sheet metal that's not 100% OE replacement, and needed some general maintenance/cleanup.
Other dated items include the head and I think the intake manifold. The engine block I think only has a casting number and an engine serial number, but I think the transmission has a date code, if you ever dig into it that far.