Congratulations on the Ishapore guns. I am not sure how familiar you are with them but here are a couple things to keep in mind if you have not encountered them before. The chambers on these guns are 7.62 NATO specification and not .308 Winchester. While this may be obvious, the practical consequences are that the headspace might be a touch longer than a .308 and will probably chamber a .308 No-Go gauge. I don't actually have a 7.62 No-Go gauge, but the .308 Field-Reject gauge is shorter and if it does not chamber that, you are good.
The chamber is also slightly larger radially, but that isn't all that obvious.
As for swapping the nose cap, keep in mind that while the pieces are going to swap without a problem, if you want good accuracy, you should probably make sure that the barrel still clears the new nose cap. Another thing to consider on SMLE type rifles (and I believe the Ishapore .308 is the same) is that under the stock, there is a barrel band which holds the barrel at about its midpoint onto the bottom of the stock. On the underside, there looks like a big screw head, but it is a cap covering a spring which applies tension to the barrel band. There should be some tension on that spring. The original springs on many SMLE type guns just don't hold up and have taken a set. I cut a small piece from a worn out M1 Garand recoil spring to replace it. The Garand recoil springs are high quality steel.
Advice comes with no guarantees (Do your research) but this worked pretty well with my Frankenstein SMLE.
- Ivan.