Honestly, based off a TR3 frame and engine orignially or not, as essentially a custom kit car, I wouldn't spend more than 14k or so for that as is, just based off of other v8 conversion cars out there. A conversion in general inst usually worth nearly as much as the amount of work it takes to do it, mostly because you have to find again when you want to sell it, someone who likes exactly the same things the original creator did.
Does it look well executed to me? sure, would i spend the 25k they're asking? unfortunately never, as for that amount there are too many other things that I'd want =)
I'll probably have close to that invested into my TR6 by the time I'm done bodywork and paint. I'm doing some customization to my 6 as well that will probably lower the 'resale potential' but it's my car, and i dont plan to be selling it =)
Looks nice, i just wouldn't call it a TR3 anymore =D Just like I wouldn't call one of those triumph herald re-body kits a herald anymore when it's done too =)