i kept all original drives and safety relay circuitry
major hurdles were learning vb scripting to control everything! there is some better info on this now but you still have to know "exactly" what you want the machine to do!
my machine is 3 axis , z is on ballscrew with pneumatic assist for the weight. also has pneumatic up /down for each head in use.
its an ongoing project as you always find things you dont like and change them, but unlike manufacturer oem controls, this is easy to do once you understand it.
(as long as you can manage the vb scripting) see artsoft videos for an insight on this.
expect a month to get it programmed to do everything. if its just routing about a week to get it all under control.
depending how flexible your brain is!
the conversion was well worth it . cost approx £1000 for parts off ebay in total but £100000 in brain labour!
im going to convert a machine similar to mine for somebody else this week. but he has to pay! i expect i can have his conversion done within 2-3 days start to finish