We have a NL only 10 team league we only use $200 budget. Its not hard to figure what it would be in a $260 cap for research purposes. 200/260 is 23% less money. So just take 23% off of the salary of player in $260 league.
What we do for keepers is you can keep them for two years at same price as drafted. The third year you can choose to keep them for one more year at that price and then lose all rights to the player the next year or sign a long term deal. Long term deals are $5 per year signed on top of what ever you paid for him.
EXAMPLE: Dexter Fowler drafted for $6 two years ago he can be kept at same for third year or sign to a 2 year contract($6+5+5=$16), 3 year($6+5+5+5=$21) and so on.
I know all this is probably to late now that season started.