72-Spoke wheels are nice and strong, and will greatly extend (or eliminate?) the need for periodic truing. One trick to lighten the wheels a bit and have the 72s look a bit more "period" on a sidescreen TR is to use a set of 15 x 5 Morgan Plus Four wheels. Same Dunlop style as TR6 wheels, but narrower and a little more vintage-looking. The 72's were optional on late '60s Plus Fours, and are commonly seen on the Supersport cars. The wheel offset (backspace) is also visually appropriate for a TR, and (typically running 165-section Vredesteins) I've never had any interference or truing issues with the set I put on my car back in the '90s.
The other trick to minimizing the weight impact of the 72-spoke wheel and tire combination is to shop around and determine the weight of the tires you are considering. Tire weight isn't always published, but is normally available if you ask. 155-section tires are what I use for a spare wheel in an early car, and I found that weight varies a lot here also. The Vredestein 155 tire on my spare weight something like 8 or 10 pounds less than a USA-made (don't remember the weight) tire that I also had handy at the time.