Asking to see if this is a possible solution.

I'm building up an old (1988) Miyata 312, and I'll be using a set of wheels that has a Shimano 7-speed freewheel (126mm spacing). I'll also be using an 8-speed Tiagra brifter on the bike. I understand the problems with the difference in spacing between the shifter and freewheel. That combination seems to work well for some and just so-so for others. I'm wondering if it would be possible to replace the spacers between the freewheel cogs with ones that would allow the 8-speed to smoothly match up? I know I'll have to set the limit screws to block the one extra click on the Tiagra. But can I improve shifting by swapping in different spacers?

Thanks for any advice!