you should be ok, as most of the longest part of your journey seems to be straightish motorway. A year or so ago, I drove from Southampton to Ascot and back, in my saracen, to do a prom for a friend, all up it was around 126miles, if I remember, all went very well, no wind-up, (not that I could detect anyway), only issues were fuel filter got a little blocked, by some residue from an anti-corrosion treatment I'd previously used, and it's thirst for petrol, I reckon I averaged 8-9mpg, which is very good for one of these.... at times I was cruising at 60mph! too, verified by my partners VW Passat....(have since checked accuracy of the VW and it over reads by 3-4mph, checked saracen, by using a sat-nav, whilst driving, and top cruising speed seems to waver between 55 and 58mph).... so as long as all your fluids are topped up (including the fluid flywheel!), tyre pressures are correct, (they are all different, front/centre/rear,... please read manual:readbook:....)
Apparently the Saracen was the best of the FV600 series when it came to road-use, with very little evidence of damage caused by wind-up.... I have heard a rainy day helps, as it allows for some slippage, but the tyres don't grip too well in very heavy rain, so watch your speed, if it starts to pour! good luck!