speedo cable vs. speed sensor on 700r4.......HELP!

[EMCC ROB]

I'm changing out the tired LG4 carbed 305 in my '86 Z28 for a built up roller tpi 305 capable of close to 330 hp. Of course, this is a lot of work ( changing over the fuel pump, lines, wiring,fans,yadda,yadda,yadda). This is worth it to me as this was my first car almost 20 years ago.
When it came to changing the eng. wiring to the speed density wiring harness, I noticed that the wiring going to the trans has a plug for the speed sensor in place of the speedo cable that I have. The wiring & the motor came out of a 91 Z28 before I rebuilt it.
My 1st question is, will this have any effect on how the motor runs due to lack of signal from this plug to the E.C.M. as I must use the cable for the speedo?
My 2nd question is, someone told me that as well as the fuel sending unit, the fuel tank will also need to be replaced as it is different inside the tank. Is this true?
Any light shed on these questions will be greatly appreciated.

[WMCCjames]

Well, the good news is that it will work, the bad news is that you will get a check engine light when the ECM doesn't receive a VSS signal from the trans. Your engine may have a tendency to stall when coming to a complete stop. It's been a long time since I have messed with that stuff, but I'm pretty sure there are "work arounds" for this. Try doing a search on Thirdgen.org
As far as the tank is concerned...the tank is fine, however you will need to upgrade the pump to a EFI pump, like a Walbro or a AC Delco for instance. You could pick up a whole new sending unit assembly that will have the pump, wiring and lines too if yours are in bad shape.

[EMCC ROB]

Thanks, I'll look into it & let you know what I find.