They're actually a simple fit and better quality than most of the newer copies, not the best for an accurate 356 dash reproduction look but pretty functional and a good value. Once you cut holes for the larger 914's, the smaller 356's no longer fit without some rework of the dash, just something to consider down the road.
The speedometer cable is a simpe connection with the VW cable and will read a few mph higher than actual with a stock diameter VW tire, but close.
Here's one sender (https://www2.cip1.com/ProductD...ductCode=VDO-221-012 ) that works with the 914 fuel guage, but check if you have the same tank.
And the temperature gauge will look good or better than the large park brake light anyway and would be a good upgrade.