The 1.8 Litre L series puts out 104 HP standard. Whack on twin carbs and some extractors and you'll probably have about 115 HP. There are plenty of 5 speed gearboxes around, the boxes will handle 115 HP easily. Electric ignitions are a bolt on fit (series 2 bluebirds). The engines are torquey as. I hardly revved my engine past 3 G. most gear changes where at about 2.5G and this was enough to keep up with most modern cars. (My L18 was in a 1100 Kg car)

To get 115 HP out of an A15 may involve considerable cost. The torque will not be as good, 5 speed gearboxes cost s*@t loads. An A15 probably weights less than an L18 but the difference would not be much.

As for the CA18... forget it!!!! Doing an EFI conversion requires a lot of work and money. Save yourself the hassle....Whack in an L18 and have fun!!!

A normally aspirated CA18 may have more power (130 HP) compared to the L18, but torque wise, the L18 is probably pretty close to the CA18. (I'm not sure)