There are a few furfies going on in this exchange about the No5 Mk1 rifle. Firstly I congratulate the OP on a great decision and an even better score on a "Jungle Carbine", you will love it and cherish as I and others already do. When you get this rifle, please visit us as at the Enfield forum in my link below and add your data to my No5 survey thread.
I would respectfully add the following ... the issues of wandering zero in the Far East campaign was in large part due to extreme moisture and humidity playing havoc with the furniture and causing the fore-end to shift unpredictably, in some cases causing contact pressure on the barrel. This in turn caused a shift in POI which varied from rifle to rifle and the conditions it experienced.
To combat this problem, later No5 Mk1's (Some early trials models also had the nose cap fitted) had the front nose cap fitted to the fore-end to stop moisture entering the end grain. Later on the Malaysians, having learned from the Australians and British during the Malaya Emergency war of the 50's, finished their No5's in varnish to avoid any chance of the furniture going soft and to ward against moisture.
The bottom line is that bedding shifted due to the effects of expansion and contraction during monsoon conditions, particularly under battle fire. The furniture would rapidly heat up and with all this heating and cooling down, mixed with humidity and rain, the bedding could shift with unpredictable results; thus zero was effected. I have commented on all this in many previous threads on the No5 ... I have also made the No5 a pet study due to my own Grandfather and Great Uncle being issued the No5 in Burma during the latter part of WW2.
If the furniture of the No5 is correctly protected from undue moisture there is no issue at all. As I have stated at Surplus and elsewhere many times; the wandering zero was largely unique to the conditions experienced in Burma - I and others have not found it an issue under normal conditions. Keep the following in mind also.
Back when the No5 was still being manufactured there was a period of time when it was seen as being the logical successor to the No4 rifle as the standard battle rifle. After performing various trials it was ( apparently ) reported that the No5 would not hold it's zero and under certain circumstances could lose it altogether. More trials were conducted and there were various reports of the lightening of the receiver being a cause of the issue as well as stocking up in some instances.
In the context of the period the rest of the world was moving toward SLR or Self Loading Rifles and many now believe that the Wandering Zero story was an expedient means of the MOD justifying re-tooling and scrapping the No5 to the Government bean counters so they could move to the SLR. After all the trials and R&D that had already been done for production of the No5 they needed an excuse for this change as Britain was now also facing a struggling post war economy unlike the U.S.
It is now widely held that the "Wandering Zero" was the excuse they required. Few if any No5 owners today find any accuracy issues with their No5 rifles, and fewer still can replicate the wandering zero - it was not a myth, but rather a circumstantial issue and this seems to be well supported by the many owners who can not find any evidence of it under fair weather and non Burmese conditions.
As regards the comment about the British paying for retaining bolt rifles in Korea - some might want to check the records of the Australian Regiment that decimated the Chinese/Koreans in the Battle of the Apple Orchard - not only outnumbered but heavens ta betsy, all while carrying No1 MkIII Lithgow SMLE's!
Best, Tiki.