One thing of note on Gew88's the bore may still be .318 despite being S marked. Interestingly it has not had the charger guides fitted, nor the receiver notched for the longer 198gr bullet. I would definitely slug that bore before firing any 198gr surplus or European ammo. A lot of them had the throats reamed larger to accept the 150gr S patrone bullet but the bores were mostly left alone and not rebarreled except for very early on. Originally the early .318 round nose bullet had major fouling issues with the long bearing surface and fairly tight .318 grooves. later the spec was changed to be a .320 groove or thereabouts to reduce wear and metallic fouling. The S patrone bullet had a relatively short bearing surface, allowing it to be swaged down slowly and not spike pressure. 198gr s.S patrone on the other hand is a different story. I shoot mine with chronographed loads up to 200fps using 218gr Spitzers pulled from 8x63 Swedish ammo, but is size them down to .318 before loading them. pretty well emulates the original m88 ammo. other than the stock being sanded, everything else looks correct, the early ones had the bolt and reciever in the white while everything else was blued. so the metal finish appears correct on that count.
Based on the look of your SMLE, it's a relatively early pre war one at 1912. LSA receiver is less common, and assuming the bore is ok and there are no significant cracks in the wood it's a pretty desirable example. As a shooter I'd want the draws to be in decent shape or you run the risk of the wood battering itself badly and cracking through the main action screw. It still has it's volley sights, or at least the screw and plate which is seen in the photo. If it's all matching i wouldn't be surprised to see over 1k for sure, in auction likely closer to $1300 or higher with the way things have gone lately. As stated above, if it's canadian marked, ad another couple hundred to the value. Overall some neat pieces!