Stage 2 heads generally use a "super 7" or 10 deg lock with a titanium retainer, I'm not familiar with an "offset" retainer but the retainer location will not have an effect on the length of the valve or the valve stem in relation to the roller tip on the rocker., If the installed height is correct on the spring and the valvetrain geometry is correct, the only option you have is to clearance the rocker arm in the spring area. The older style T&D's do not have a relief milled into them and the newer ones do, you may just have an older style set of rockers that necessitate clearance when using a solid roller spring / retainer.
Bill