Best way to jack up 1973 Dart Sport

Hey everyone, I bought 4 roller dollies to put the 73 Dart Sport up on so I can tuck the car away for the season. It has painted bumpers so I really don't want to use a bumper jack and all I have is a 2 ton roller floor jack and it doesn't lift it up high enough to clear the 5 inch height of the dolly decks. Can I put a block of wood under the k-member to give my jack more clearance or is there a safe way to jack up on the sides? where is the best place to place the jack? Looking for constructive opinions and thoughts.
Thanks in advance