What period are Lectrons allowed?
Early Lectrons didn't have powerjet and a 36mm was fitted to the 1977 Penton 250
and so an early 36mm non-powerjet Lectron is ok for Pre 78.
This one has powerjet which is ok for Pre 80 and later.
If you are going to try Lectrons then you will need a Lectron parts supplier.
I have used FastByGast (FBG) and HTG Racing in the US and Helmut Klassen in Canada.
You will need to get a few extra rods to get the jetting right.
Best to buy them new as the quality control was bad in the past.
The powerjet is a Mikuni pilot jet. Don't go smaller than 30 or larger than 90.
Start at 60 or 70 and go down in 10s until it is close then use *5s (eg 45, 55 etc) to fine tune on the day.
The plastic float bowls distort and so you may need to get a new one to stop it leaking.
Some of the new float bowls have orings which helps and FBG sells alloy float bowl stiffeners.