Your action sounds like the Ishapore 2A, which was essentially a No.1 Mk.III with upgraded metallurgy chambered for the 7.62x51 NATO cartridge. If you're a fan of the SMLE, it's definitely worth some effort, and will make a very rugged and servicable hunting rifle.
Besides what rbernie said, my experience with my own 2A has been very positive. It's quite accurate with match ammunition, and at least on par with the vast majority of surplus BAs with service loads. I bought mine because .303 surplus had gotten fairly expensive and hard to find and I missed plinking with my SMLEs.
Numrich would be a good place to start for parts, whether you wanted to "restore" it to issue trim or not. IMO, it'd pretty much be a toss-up, costwise, for a basic job either way.
As far as customizing goes, there's a pretty sizable aftermarket supply of sporter stock sets in wood or synthetic, iron sights, scope mounts, etc. Brownell's catalog will give you lots of ideas and options which you can filter through as your tastes and budget dictate. There are at least a couple of high-quality "no gunsmithing" scope mount options and a whole raft of choices when it comes to irons. At least two other options besides "Pro Mag" for standard and five-round hunting mags, too. There are a lot more viable DIY metal finishing choices now than ever before, and they have those covered too.
Sound like a nifty project, especially when the biggest necessity was donated. Let us know how it goes.