The retainer kit we are using (TFS-2500286P) has shorter valve seals than stock to clear the additional compression of the spring from the additional lobe lift of the cam.

An accurate measuring device like a small mechanic’s ruler or a set of calipers, a valvespring compression tool, and a few hand tools are all that’s required.

It's a good idea to lightly tap the retainers with a soft mallet to loosen the valve locks and then bolt the spring compressor tool in place over the pair of valves.