I will also be fabricating a custom instrument cluster for my 72 buick skylark, it will be a stainless panel that fits in place of the factory instrument panel and will accept a 5 inch speedo and 5 inch tach, and four spots for 2 5/8 gauges. If you have any interest in one of these let me know and i will get in gear and build if no interest, I will wait untill spring. as far as cost goes, i wont know for sure untill i am finished with mine.
