Even assuming you could find reasonably priced riser blocks "AND" the parts necessary to make the tailstock locking mechanism function properly, you would still have a problem of the motor.
Presumably, the desire for greater swing is to have the capability to turn bigger heavier stock. A number of folks have already reported that the JET mini motor is only marginally strong enough to spin projects of the size of the Jet's maximum capability. Trying to turn even bigger stuff would be a real risk and installing a larger motor on the mini would be added cost and mechanical difficulty.
Jeff Powell, who posts here on occasion, has reported on another forum that he rotated the headstock on his JET mini (I think it was the VS) 180° so he could turn stuff outboard. He claimed he had no problems; but there is a serious safety issue involved in that configuration that I personally would prefer to avoid. The safety issue could be resolved by rewiring the motor control so the motor would run backward; but that is a whole nother ball of wax.
Bottom line.....your smartest move.....if you want more swing is to take dance lessons. Oops...just kidding[
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] Save up your pennies and buy a bigger lathe.