I think only the seats are the most difficult to retrofit. Yup I know there are quite a bit of differences but in terms of cosmetics mostly. Here's what I think would work from the 30K saved:
M5 or M-tech bodykit FRP material = RM4,500
19" sport rims with tyres = RM8,500
M-Sport steering wheels (used) = RM2,000
LCI rear light conversion = RM3,500
Bilstein shocks/absorbers = RM6,000
Total = RM24,500
Just a rough figure and trying to think if it makes sense, haha. I know I'll lose that wonderful sport seats, head lining and trims. Another thing is that some High Line have sun roof and carbon fibre trims interior which some M-Sports doesn't have

If I have the money, I'll just go for the LCI and problem resolved.