With the best quality Ti-17 Professional Grade Retainrs the retainer OD is smaller than the spring OD. There is no reason for the retainer to be as large or larger than the spring.
AS was said, You may have raocker arm geometry issues from a pushrod that is too short. Don't just buy a longer pushrod. Check them for correct geometry using a good adjustable checking pushrod and the principles at Jim Miller's Mid Lift webpage.
Rockers can be carefully cut for correct spring clearance if all is in alignmnet and the geometry is correct.
Ed