originalshinkicker on here is something of an SBDU expert, failing which there is the SBDU Yahoo group
Given it's rarity, I would be inclined to go back to original, even if it means waiting until funds permit (if I had won it on eBay then that was my intention)
Even if you went back to TI Red, and got the decals from H Lloyd or similar, it probably wouldn't run into a great deal, and it would mean it had it's identity back.
It has clearly been painted at some point, and the head badge changed, as the one it has didn't appear until the 80's (if you carefully remove it you should find the original rivet holes for the older badge)