Really bogging down in 3rd gear

Well, you gotta start somewhere, I suppose. And with points, no ignition module of course.

If the OP can confirm, it basicaly only runs Ok at higher revs in 2nd? I would certainly be looking at the points gap; have them close up will cause symptoms similar to this. Also, when you put in the points last time, did you put the correct lubricant on the points and the points cam on the distributor shaft? You can't use just anything; the points rubbing block will wear down and close the gap, and if you use certain lubes like lithium, it can actually wear the sharp angles off of the shaft cam very rapidly.

Next on my list would be a vaccum leak.

Then timing. That is just an ordering of things to check, not that it is any one in particular.

If you are planning to do the tank and lines any way, it is certainly an excellent idea. I recall this car had set for quite a while.