I would think with the slower speed of the older vehicle, you could swap the weights to the back side of the wheel and still be fine. All of the newer vehicles with aluminum wheels are balanced with stick-on weights on the back side of the wheel. Even when I had tires and balance on my '78 Vette with factory aluminum wheels that is how it was done.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy