Blimey you have long legs there! I'm 6ft 3in and I run my saddle 81.5cm from the BB centre (36.5" inseam), and there's enough seatpost in my frame. Might be worth looking at a deeper rail saddle to get that extra few mm of insertion. The seatpost needs to be 10mm below the bottom of the top tube (which is around 100-110mm depending on the frame size). However, in terms of the length of lever, assuming you've got that minimum insertion you'll not have a problem as the only frame I've ever broke due to seatpost leverage was a 953 sample which was way too thin at the top of the seat tube, but was the thickest tube Reynolds did. Never, ever done a Soul, and one part of the CEN regs covers this with a 50,000 cycle fatigue test.
Onto other stuff – nice bike Deano. Glad Samways saw you right.
The guy looking to replace his Inbred – 100mm works great, particularly for singletrack and more rolling terrain. Don't worry about the forks you have; get a Soul and use them. It'll be good.
Sizing Advice – The guy's who's 5ft 10in? You need a medium. No doubt. Our medium/large crossover happens around the 6ft mark.