Gunk *in* the carb bowls isn't much of a problem - at least until it fills up the bottom of the bowl to the level where the jet tube attaches (HS6's - right?) They probably designed it that way on purpose. What you need to prevent is *new* grit coming in from the fuel lines - that is the stuff that can get caught in the needle valves on the way into the carbs. You might toss on a fuel filter between the pump and carbs if you are worried about it.

As for the timing keep a 7/16 box end handy. When tweaking the timing on mine I adjust the pinch bolt to where the dist can be turned by hand, but won't move on it's own. Then drive it a little bit, pull over and nudge it one way or another (clockwise to retard, counterclockwise to advance). Basically advance it until one of the following occurs:
1) Kick-back against the starter when cranking
2) light pinging
3) loss of power (some engines just won't ping, but advance them too far and power drops off)
Once you get the timing decent snug the bolt with the wrench.

While driving it back home try to use a *light* foot on the brakes. Plan ahead so you don't have to stop quickly. I'm just saying this because calipers tend to get sticky when they sit around. And once you squeeze them hard they might stick 'on'. You can 'stress test' the brakes later on at home. I'd be leery of a sticking parking brake cable too.
--
I'm JohnMc, and I approved this message.