I think you should go for it but as said above the rifle has the correct rear sight and "ears" already. You are lucky to have a lot of good bits there such as the volley sights and early magazine! But you may want to carefully consider spending more than the purchase price of another complete, correct and original SHTLE Mk I*** on an incorrect restoration back to Mk 1*** standards that would always be given away by the CR prefix and the re-serial when it would be a little easier to do an authentic CR series restoration and still have an awesome rifle anyway. Either way a restoration certainly enhances rather than decreases the value of a sporter but whether a "correct" Irish restoration will be worth more sort of depends on how discerning the collectors of the future will be.

If you would like to find out more there is a goodly amount written about the Irish ER, CR, and G series rifles and the interesting history behind them here and on gunboards also.

Also, I hate to say this but I believe the bayonet in the picture (if it is the one you were referencing) is not a Pattern 1907 bayonet for the SMLE but a Pattern 1913 bayonet for the Pattern 1914 rifle or the US Rifle, Model of 1917 as demonstrated by the two grooves in the grips to differentiate it from the P1907 for that very reason and unfortunately will not fit your rifle when you do get the correct MkI nose cap.