id say if it comes down to sr or ca go ca in my opinion it is just a way better engine they both have a near square bore to stroke ratio the ca just seemed to find the "sweet spot" so to speak with an 83.6 x 83 mm and in stock form can rev around 9000 rpm where as the sr is around 86 x 86 if i remember correctly and please correct me if im wrong it just cant rev as easily and is prone to throwing a rod if over revved i would suggest if you do an sr use a rev limiter at around 7500 rpm because the engine is useless after this in stock form and it will only break any higher in the rev range while it is a great engine and if put together properly can definitely be a ridiculously fast car especially in a car as light as yours i would choose the ca in the end it is your car and the decision is yours and any engine will make your car stupid fast so build it, race break it, repeat