I favour the weatherstrips sold by Fitchetts for Triumph Spitfire. They are too long, but easily cut down to fit. Crucially they have the cast in recesses of the OE part that make clip fitting easy.
Clips can be had from a number of sellers including Fitchetts, no worries there. BTW the ones shown in Graham's first link are inner strip clips (GHF 1582) and not the ones you need for the outers which is GHF 1580.
Actually fitting them needs practice and patience but is not really tricky if you have quality parts. I use a Herald/Spitfire front wishbone shim (less than £1, also from Fitchetts) as a clip fitting tool grasped firmly in a mole grip and initially fit the clips to the doors with a thin, flat nosed pliers, then holding each clip up individually with the tool, starting at one end push the strip into the clip with thumb pressure a bit till all clips are engaged, then go back and push each down fully. I like to do this with the doorcard removed, just in case I lose a clip in the door bottom, but it doesn't happen much these days. I can usually fit all 4 strips in 30 mins and never lose a clip.
Thanks for the help. Quick question, Fitchetts only have weatherstrip for the R/H side available and I am doing a nearside door. Can I cut up the R/H strip to fit?