This has become a really good discussion thread as all of us are coming up with our favorite theories & some really usefull info & arguments are being presented.

I think that we would all agree that engine choice must be directly linked to budget & it's the size of the budget that drives the degree of choice available.
For those of us on more modest budgets, i see the choice focusing on the "A" series versus "L" series debate, & this is to some degree dependant on ones workshop & it's capabilities.

The "A" series has many adherants, oncluding me, & is the easiest to fit, since the B10 series of chassis came with one anyway. They are plentifull, & cheap, & performance parts are also reasonably plentifull. By using the A14/15 engine with even the modest OEM type Webber carb & a set of pipes, performance can be noticeably improved at a very modest cost. These engines can be built to provide very substantial power improvements, but the cost involved allows us to look at other ways of uprating vehicle performance with a lower stressed engine.

L18_B110 offers a very convincing argument for the "L" series conversion, yet it is not one of the more popular ones. Perhaps we should re-read his comments in this, & other threads, more carefully as it looks to have a lot to offer. He is speaking from personal experience & does not seem to be even thinking of switching away from this combination. Perhaps he clearly remembers to old addage,"When you're on a good thing, stick to it."

The CA18DE conversions are quite a bit more involved, & expensive, yet offer a lot of performance once it is properly done. They are really impressive when showing off the engine bay, but have the potential to get the less experienced driver into a great deal of drama if not carefull.
This is probably the best way to bring a 30 year old chassis into the new century, but it won't be quick, easy, or cheap.

So Stevo & Feral seem to have it covered fairly well. An "A" series for a mild streeter, the CA for something quite serious, but i would suggest that for those on a modest, to medium budget, the L18, & possibly the L20b, has a lot to offer, including a readily available engine at a very modest cost. Proven reliability, with the potential to develop good strong street power, & the bonus of a relatively simple conversion. This engine sort of fits in the middle for those who want strong street performance, & don't have the budget for top end race development. Even Feral runs a "L16" in his streeter Sunny coupe. At least, that's what i says on the cam cover

What do you think, [yes,..you] does this simplify the overall situation, or complicate it?