I have not read everything here, so the theme may have changed over to grouse shooting with Tornado fighter planes for all I know.
But just to put in the longest and steepest in Scotland I have been on:
Cairn O Mount from the west, also called Cairn Na Mount on page 1, is the steepest climb I have ever done. The two steepest hills on this climb felt like 90 degrees, but was probably around 20 degrees or there about. In baking sunshine, it was like a sauna. The middle section too was pretty heavy. It has some fantastic views from the top.
Cairn O Mount is best approached from the west; the village Fettercairn and the whisky distillery to be precise. There is a good coastal road going down from Stonehaven though to Montrose and I would highly recommend a combo of these two roads in one tour. Then back to Aberdeen or Stonehaven via Banchory.
Lecht Pass is also a totally vertical in two steep steps. Start point is Ballatar and the end point is Tomintoul, one of the finest Highland villages there is. This pass is also best combined with the mountain pass from Brown Bridge over to Grantown on Spey.
The road up to Rest And Be Thankful from Arrochar towards Inverarey or the Gowal Peninsula is also a good climb. Very scenic over some miles. The best start is Glasgow and then 'doon the river to Dumbarton and up Loch Lomond to Arrochar and this hill. Return down Loch Fyne to Dunoon, ferry to Gourock and back to Glasgow. The climb is not too bad, but it is very scenic in the Arrochar Alps.
The Cowal Peninsula is the climbers paradise with several severe climbs. Start point is Dunoon.
Isle Of Arran too has some snacky climbs. To be precise; the String Road.