The L 20 B is about 50 lbs heavier over all.
I run them in everything from Datsun's to MGBs.
Have run them in 3 past Zukes that we have owned with amazing results.
I ran the Datsun Dog leg 5 speed in 2 of them and the drop pan 4 speed in the other.
Upgrades for the "L" motors are prevalent and cheap. Tones of info out there in cyber land.
The first we built was a stock engine running a Yota 3TC carb. It averaged 28 -30 mpg over a 3 year period.
The next two were built for pure HP and still managed about 20-25mpg.
The conversions are pretty straight forward. Similar motor mounts. The L-20 isn't a cross flow head so it is a bit tight on the drivers side but not bad. We run electric fans rather than off the motor to compensate for the added length of the engine (3.50").
Stock Zuke radiator. Wiring is a no brainier.
Exhaust dump is similar as far as location. ETC. ETC. ETC.
The thing about the L motor is that HP and torque gains are very easy to accomplish.
And it will spool all day long......
Here is a picture of a SSS L 18 we just installed in a 1966 MGB.
The duel SU's don't work well off road.....
I just started the new engine for my Zuke. It is an Asian market L20 with an A87 head , cam , Bob Sharp 4 bbl intake , and a few other secrets I won't get into here. 200hp is the target..... economy be damed....Boxcar...
PS: Datsun has a great 3 spd automatic that fits well in the Sammy........