The best thing to do is to do a search to see what others are using for the same exact plane you have. After being in this hobby for about 22 years I do the same thing. I check to see what others are using and copy. I get to see the mods they made to make it work and I also get to see what failed and what held up. Robarts are tricky because it depends what series of gears you use for a particular model. Has to do with weight.That determines if they will hold up or bend on a not so perfect landing which we all have from time to time. I also use gears from here which are a lot stronger than Robarts. You just have to worry if your wing will hold up because they not going to bend that easy.
http://store.laser-design-services.c...e8fd2066e52fed
Do a check on ebay too..you might find some thing better.
http://cgi.ebay.com/Air-Retract-Land...item4cf291df4c