you can use a 4cylinder t5 you just need an adapter pilot bearing

a lot of the 5.0 guys run them no problems and with you being stock you can save some money going this route iirc the torque ratings are the same as the non world class v8 t5's

 

What I did was getting a rebuilt T5 from eBay (streetcarz performance). i paid 750$ for a great unit. No idea if cheap or not. I love that box, he threw inj a used shifter as well when I asked. you need that
All other parts I got from NPD. I used my old bellhousing and the adapter plate.

The problems I ran in:
a) the screws for gearbox to adapter plate were too long. In my case i cut 2 and for the other 2 i used washers. They're only long by a little, but it's enough to get the gearbox in slanted. watch out for that. the screws from gearbox (4) to plate MUST NOT touch the original bellhousing
b) driveshaft. I had an old I6 originally so nothing fitted. I bought a used driveshaft from a 66 289 auto that fit
c) you might have to cut your old driveshaft by 3/4". No way to tell before you do the swap. Put it in and see from there ...
d) i thought it fitted fine without cutting the transmission tunnel. don't be fooled by good looks. It touches the tunnel ever so slightly and you end up with horrible vibrations. You will need to cut a bit out of the tunnel. In my case it was half inch front and half inch right