Been there done that. I learned to start it with my left leg standing next to it. It had a 1 1/2 inch GP carb and road racing cams. I had a hematoma in my left calf for years after trading it for an A10 Spitfire. Much nicer to ride and start. I was 16 years old then, 77 now. I loved the sound of the large short megaphone on deceleration.
Jumping up and down on the centre stand will push it through the frame tube that it uses as a stop. Better to start off the stand, as the stand is only strong enough for the static weight of the bike. My B33 had holes punched right through the tube by the stand that took quite a bit of repairing. Beautiful bike, a credit to you.
Isn’t that starting difficulty the reason for the demise of British manufactured motorcycles and the explosion of neater and easier Japanese models? Now the same bikes are being reborn, from India. But with electric starters and computers. I had a 1958 Thunderbird in 1964.
Many a rider in fifties & sixties forgot to retard the ign timing and nearly got to moon before Buzz Aldrin after bike kicked back some even got broken legs I believe !
So my grandpa has one of these (plus like another 7 other bikes) and he's made it very very clear that when he's gone if you can't start it, you can't have it.