converting my parkson 1na

[mcmental76]

hi there im currently in the process of converting my parkson 1na, now my mill has no quill so my first option was to try and lift the knee as the Z axis but as you can imagine that is very heavy! the spindle (int40) speed has 1250 rpm as its max so im debating about building a seperate head with its own spindle on that can produce higher rpm and this is wherre your advice comes into play!! do i
A; buy a seperate spindle, either er25,32,bt40 and use pulley and belts??
B; buy 1 of those air cooled spindles that has a motor built in and run with a vfd??