Jep, check out the following group: http://home.att.net/~jweir/tbi/inject.htm
and go to the Howell Users Page. I just finished installing a junkyard TBI buildup on my 258 and love it. These guys and gals have been invaluable help. In answer to your direct question, I would not go with Howell, rather I would do a junkyard buildup (rebuild everything) ) and go with a Painless wiring harness (thats what I did, I am very happy with the Painless product).
It is a little cheaper to go junkin, but dont skimp on the harness.I have the painless kit on mine, but I'll never be guilty of that again!!! Howell at least knows what is wrong if you have a problem.there a little more expensive, but they know there stuff.Painless hasnt a clue what else works with their harness other than what they tried it on!! Just my $.02 worth.