First, I would not let Passon touch anything of mine. Second, if you are a decent mechanic, do it yourself as mentioned below. I converted my car to a four speed about 20 years ago with a used transmission. I rebuilt it myself. It was VERY easy.
Totally agree.
You will only need some good snap ring pliers and regular hand tools. I had an article from an old Mopar Muscle Magazine and pages printed out from a repair manual. I did take a shaft down to a local transmission to have them press a bearing off and on. I had them install some synchonizers that went on that shaft while they were at it. I did everything else myself.