do NOT get the metal-bodied spokeshave with the knurled adjusting nuts. If you project the curve of the body, the nuts will be right in your way. I found this true even with a flat-bodied shave - the body could follow a tighter inside curve than the nuts permitted, so I'd start out fine for the first inch or so, then run into interference.

I moved to a Stanley 52 (adjust by guess), the commoner pattern being the 51 (51: gull wing handles; 52: straight handles).

Even this can't handle some inside curves. I recently acquired a Kelly Toolworks repro of the Millers Falls cigar shave, which I am still learning to use but which seems great for tighter inside curves than other shaves can handle.

But all this is probably irrelevant if you're expecting limited use. Have you considered a rasp (half-round or round), followed by a scraper or [bad word alert!] sandpaper? Rasps are amazingly versatile tools, and not too expensive ($20-30 for a common or garden variety rasp - though, of course, you can get expensive with these too). You won't want to sell it after - uses are always coming up for a rasp.