That looks to be a pretty nice 66-1 with little/minor wear. $800 might be a bit steep for a standard 6" P&R 66-1, however it does have the matching box and correct grips. In my area, the price would be pretty spot on. If you want it, go for it, I say.
I must add that there are in fact, 66-1's that are considered "transitional models" that were either pinned and not recessed, or recessed, but not pinned; around 1982-83. These were produced during the engineering change from 66-1 to 66-2. There were also a few select 66-2 transitional models, but I've seen more of the dash 1's. I have seen a handful of these transitional models in the past few years in all barrel lengths, particularly on GB.
I also must add that there are a select grouping of 6" 66-1's from around 1978-79 that have 6 1/8" barrels. The standard 6" 66 barrel was actually closer to 5 7/8". SCSW states that these are worth a 20% premium. If you can, take a tape measure when you go look at it, and measure from the cylinder face to the end of the barrel.
36K serial number would put it at 1978-79 production date, so it very well could fall into this special category. I have one of the 6 1/8" barrels, a 4", and a 2 1/2". Love each of them. Good luck and keep us posted!