If you have all the parts or most of them for the SD swap, then why not to it. From someone that has actually done it on 2 different pickups now, it's not that bad. Both truck I did it on just because I had everything I needed to do the swap already. If you're wanting something interum till you go big, then just run a SD turbo for a while, then find the right deal on a 38R, then go big.
To swap, you need the only the driver's side SD exhaust manifold. The pass side is the same. 3" plenums, SD up-pipes, ped, etc etc. If you already have to turbo and it's a stock SD truck turbo, then you'll need to mod the flange on your downpipe by welding on a SD flange. If you have or can get a 1.15 housing for that SD turbo, then use your OBS EBPV/dp flange. The 3" OBS downpipe will have to be dimpled a little along with the pass side up-pipe in order to clear each other.
You'll also have to massage the firewall a good deal behind the turbo and above it to clear the SD turbo since it sits taller than the stock OBS.
I don't think it's a bad thing to do and it gives you good practice in being up on top of the motor. Or go the easy D66 route for now. Either way, I don't think you can go wrong. If you wanna swap to SD stuff just do it and don't let anyone talk you out of it. I did it for kicks cause I had everything I needed already. Everyone told me not to, but I'm glad I did and would do it again as an interum step. I don't honestly think I'd ever go back to a stock OBS turbo setup ever again!! Within the next year, I'm going to be pulling my stuff off and going to a T4i flange GQSSB or KASB.
