no replacement 4 displacement?????????

[DDSR240]

Does anyone no if Mahle offers a standard bore for the sr20. Sounds simple and believe me I have searched only to find the smallest bore being 86.5, im worried because I ordered them friday and the shop owner was on the phone with his retailer and told me 3 times I must do a overbore on my block b/c Mahle doesnt offer a stock bore piston. wtf so I told him to get me cp pistons then because I'm going for big numbers and don't want to risk weakening (I heard they tend to oval at 600+)my stock sleeves. Then he said never mind they do have them in stock bore,so I ordered them and thought nothing more of it till I got home and started searching. Every site I saw offered them at a minimum 86.5 bore exept one that was stock bore but the stroke was listed at 86.5?? so I am assuming that site was a typo. I really want to use these pistons for there lightness strength and the coatings they come with so if they arn't availible in 86.0 trim should I go ahead and do the .5 over bore and is it safe on the stock sleeves for 550 -600 hp?