Perhaps if you don't have enough Points+Credits for a Standard Award now the best strategy would be to create a new .25 credit, transfer that to Southwest maximizing the length of time you have to create a have Standard Award and minimizing the amount you have at risk then allowing all of the credits to be converted to points.

I'm not exactly sure how you would designate specific credits to transfer, but Airtran has in the past been first in first out. So creating .25 credit with 300 points transferring alll of your credits to Southwest then transferring 7 Credits back to Airtran ought to leave you with the new .25 credit in you RR account and the 7 (or more) credits would be converted to points.

If I have time to fiddle with it I'll test it out. I'm eventually planning on transferring enough points to create a new Standard Award and leaving .25 credit to seed a Standard Award later.