Do i need to modify the original propshaft?
I am fitting 2.0 pinto and type 9 box.
If so can anyone tell me what needs to be done and who best to do it.

Yes, it will need to be shortened.

MK Sportscars will do this for about £60 exchange.

In short, fit engine, gearbox and diff, measure between diff flange and g'boox flange. Take sierra prob to local eng comp to have it shortened to measured length.

should do..