Yes and Yes.... Painless does make stand-alone engine swap wiring harness.
I used a painless harness on my 1999 5.7 vortec swap over to my 86 FJ60. I'm sure they have a harness that works for TBI. My experience with my harness...very well made, no loose connnections or missing plugs, good instructions manual.
Problem was in my case that the painless harness for 5.7 vortecs was made to only work with certain year model PCM's... this information was not properly disclosed in the literature. I ended up have to get a PCM from a 97 year model truck with 5.7 vortec (apparently there is a difference in the pin outs / electical connections from teh harness to the PCM in teh 98-99 year model).
I'm sure that painless makes a harness for TBI...you just need to go to their web site and check it out...I don't recall that one to be very expensive. I would also check with teh Howell web site to see what they make.
Remember the painless harnes is a stand alone engine harness (at least in my case) so I expect the same for the TBI setup. All you have to do is supply 12 volts and ign on signal and you're ready to go (simplistic explanation). You'll have to figure out teh Alt wiring too. Also another key point is to make sure of what you plan to keep working on the donor 5.7 TBI engine as far as emissions stuff like the o2 sensor. On the TBI engine I would sugguest that you keep everything functional since its rather easy to do so. You will or may need to have a new chip made for your ECM....especially if you change transmissions or make other modificaitons to the engine transmission that your TBI ECM expects to see (example changing from auto transmission to manual, or deleting emission controls & EGR). There is a web site that I don't recall the address to..right off hand but I'm sure someone can post it up where the guy deals with TBI engine ECMs...
On my truck I labeled the pos and neg side of the coil, the A/c wires, and Alt wires. I did away with all of the emissions stuff. Basically I disconnected all teh wiring and tied it up out of the way, and removed all the Toyota fuel evap stuff, emissions stuff. Don't cut any wires or damage anythign as you may can sell some of it and you may or will use some of hte wiring related to the A/c compressor, the Alternator and the coil potentially. Plus you might be able to sale some of that stuff you do need.
Painless harness is not hard to install... Read the instruction manual a couple of times and make sure your know what is what especially if you are new to working on cars.