Hello mate & welcome!!
I have an s510 at the moment and I really like it!! I have an ags on it at the minute on medium mounts the clearance is not a problem at all!!!
All u haveto do is try the mounts and see which ones feel the best when your head is rested on the stock!!!
What tube scope have you got at the minute? I'll have a look see if I have some spare mounts
Adam