Well, they've already converted one for Colombia and 3 x 767-300ER MRTT aircraft are on order for Brazil's KC-X2 programme.
767-200ER seems a better idea (as I proposed back in 1996!), given its shorter fuselage for boom clearance on take-off and lower structural weight.
Israeli 707s were through Lajes AFB last week, supporting an F-15 trail. According to the spotters, they were also supporting Jordanian F-16s....??