You didn't resize him...you just shifted the sprites down. It doesn't work that way; in fact, that made it look worse.
Anyway, reclassifying it as an alpha is a step in the right direction, but if you seriously want to pursue this, this will need TONS more work. This wad isn't even a complete set of frames. Plus, it just replaces sprites; it's not an individual character. To do things properly, you need a MAINCFG/OBJCTCFG lump and an S_SKIN lump. Then, you'll need to resize it for real. In the meantime, you could set HIRES to 1, which would at least make the sprites closer to the proper size. Then, you'll need to realign the frames, and, above all, you need to spend more work ON the frames.
Before you say "oh, I'm new at this, please don't be so harsh", I'm not trying to BE harsh. I'm trying to point out what you should do BECAUSE you're new. This WAD needs a lot of improvement, so try taking the steps I have mentioned if you really want a chance of releasing this.