Gauge size?

I have repowered a Maxum with F115 4-stroke and have the stock Faria/Maxum 4.5" speedo and tach set, what size are the yamaha 4-stroke speedo and tach's? If the yamaha speedo and tach only come in the 3.5" size what can I do to make the dash look right. Any help would be appreciated.

[boats.net]

The Yamaha gauges are the 3.5 gauges requires a 3 3/8 hole. May have to make a dash panel using Starboard plastic panel.