recent rebuild rough shifting

[RBrandon]

My 98 GJC with new engine (replaced block, rebuilt the rest) is shifting a little rough. It is only about 330 miles into its break-in period. I have two culprits I am looking at but I wanted some ideas in case there's something obvious I am missing. The TV 'kickdown' cable is one thing I am looking into. I broke the grommet off the end and rigged it to get it back on the button / post. I adjusted all the slack out I could bet my rigging doesn't allow the cable end to pivot freely around the button it hooks to so it keeps a little slack once you manipulate the throttle. So I figure that will have to be replaced although it doesn't look like an in-stock item at any of the local parts stores. Then there is the speed sensor on the output side of the tranny. It went out once before with very similar symptoms. I have no code saying it's out but at 16 dollars for the expensive one I figure it could use replacing any way since it has high mileage on it. Any other culprits aside from proper fluid levels? Here is another question: I feel more than see a timing issue. I can't put my finger on it exactly but if any one knows what the timing is on a straight six I would appreciate it. (i.e. 12 degrees BTDC, etc.) I am a little unnerved that I put everything back together from a short block and all I had to do was adjust my distributor 180 out to crank her up. I feel like any problems I am having with my percieved timing issue and the shifting is related. The only other two things I can think of would be the hall-effect sensor on the distributor and the crankshaft position sensor on the bell housing, although I would think I would have many-a-greater problems if either of those were out. (e.g. no firing of the injectors, etc...) Any suggestions are welcome as usual. Thanks.

update: got the speed sensor and new throttle valve cable and will install them saturday morning (first chance to work on vehicle when it's not piping hot under there...) to see if it helps. I am thinking now that the cable is the main culprit. I adjusted it tonight and took a quick run up and down the road and it was a little better but still not normal.