Bill Sherwood weighed a t series celica split case alloy box at 25kgs dry if that helps.

For something different Atkings rotary whos been tuning rotaries since 1972 in the states, rates the bare 13b at 104kgs without waterpump, starter, manifolds, flywheel, clutch etc.
so maybe thats why Gary hamiltons 1000 is so fast round those curves, especially with the Peri-feral 330hp he claims.

I just got a downdraught 51mm IDA weber and a 45 sidedraft weber to suit a 13b and 10a respectively.
A full extend port (torquier from low rpm) 13b can produce 230hp with the 51 ida and tuned extractors. As where a 10a (to stay in the 2ltr and under class) with the sidedraft will only make 145hp unless I go for a 210hp Peripheral port. As for the amount of work required to fit the 13b as opposed an L18 thats a different challenge.

Thanks for your hard work, this will give us a better measure for what we need to consider.

Did you mod your tunnel for the box to fit or did you have an auto tunnel that made the difference in clearances??