[1987M505]

I'm looking at a 1969 912. Repainted original Tangerine Orange with windows/seals out/fenders off. I would rate paint 7.5 out of 10 and interior 9/10. There is one rust spot in each rocker in the door jam under the rubber on the sill area. Each side is about 1.5 inches diameter and is rusted through. The passenger floor has an area about 10 inches long and 2.5 inches wide that is rusted through but looks like it has been treated and sealed. IT looks like something must have been spilled inside the car and sat in that area of the pan. All suspenion points look solid and dry as well as the front compartment, battery tray, etc...

Here's the big question. I didn't do a compression test on the engine but at low RPM's it's a bit doggy. It sputters a little. The engine was hot when I got there to check it out so I didn't get a cold start on it. It wasn't smoking excessively. The seller did plugs, plug wires, dist cap and said he rebuilt the carbs. He said the the left carb was still out of adjustment and needed to by synchronized to take care of the sputter low RPM issue. He also said it could be sucking air at the intake gasket... Any thoughts on this? I know, I know, Get a PPI. I'm just new to this carb thing. The engine pulls great and the car shifts so smooth... Just need some thoughts on the lagging at lower rpms?