121" components on 136" rails?

I'm in the process of extending my 2000 ZRT to a 144". I Have a set of 136" rails and a set of 136 to 144 extensions. I worked over the weekend to swap the components from my current 121 to the new rails and ran into a bit of a quandary. The front arm, shock and compontents bolted right up with no issues. The question comes in mounting the rear arm, shock and such. I can see where the previously components were mounted on the 136" rails and have found that the mounting position for the rear arm and shock mount are 1" further apart than they were on my 121 rails. On my 121 rails the mearsurement was basically 19 inches between while the new 136 rails measure 20" between mounting points. Outside of a slightly stiffer suspension will this cause any issues. If I leave it this way will I need to compensate for the tunnel mounting location as the top mount will sit slightly lower? Or should I drill out a new hole in the rails @ 19 inches like it was on the originals? if so which mounting location should be moved in closer, front or back.

Hope this all makes sense.

Thanks for any help

If it helps, the rails are from a 00 / 01 pantera.

Got it figured out! The pantera rails were missing about 6 holes. Measured twice, drilled once! All put together and ready to go in.