Holiday - one the issue of the Jungle Carbine you will need to be certain it is an actual Mk5, not a cut down Mk4 or other model made to look like the Jungle Carbine. And I think $275 is a bit pricey. I wish I could tell youhow to make certain it is a real Mk5 - maybe if you look thorugh this mil-surp forum at some of the earlier posts I believe there may have been some discussion as to how to tell it it is a real one and not a 'bubba' job on a Mk4.
Some of them were not known to be accurate at all and almost a waste of an action. Check the barrel length on that rifle - it should be 20" or better, as that is the shortest length the 303 Brit will be accurate in (I believe) but please look for those other posts to help clarify that.
The real Jungle Carbines should be marked as a Mk5. If it has any other markings it might be a phoney. If it is a phoney, but has at least a 20" barrel, it should still shoot well enough to be a good truck or brush gun, and there is nothing wrong with the 303 British cartidge.
I just hope this helps a bit and doesn't sidetrack or confuse you. Also, I believe there was an artilce in the Shotgun News (in recent memory) by the Gun Guy about the Jungle Carbines - you might be able to pull that up from the net. HTH. Mikey.