Cycling Fitness / Training Advice

Well I suppose it's all subjective, isn't it...? I would describe 'comfortable' as pushing hard but not breathing hard/hanging on for dear life/wishing for death. I've only ever done one 10 mile TT effort and I've not come close to that level of effort in a long time. Confession: I haven't tested FTP in a while, I just use the WKO4 mFTP, so it may be a bit lower than it ought to be.

Last two weeks have been:
63 miles, 4000ft, 0.84 IF;
40 miles, 1500ft, 0.9 (pushing hard on the way back);
75 miles, 4000ft, 0.85 (felt hard because I was still tired from the previous one);
45 miles, 2000ft, 0.91

• a few odd 25-30 miles at 0.9ish (with intervals).
  
  

Based on how I've felt on the longer rides, I don't think my performance would drop much over another 25 miles. I'm hopefully riding a 40 mile chaingang later today, which may give me an idea of whether my IF/FTP is accurate...