Need help choosing heads (and plugs) for my rebuild.

[azimech49]

Hello and thanks for reading!

I'm currently rebuilding my daily driver EFI 94 bug. (ring snapped, a piston broke and some other stuff). I'm planning to build an engine from scratch as a hobby in about 10 months, but I want to have it up and running as soon as I can, with nothing crazy yet and keep both engines.

It's pretty much stock right now. Only change was replacing the original BERU coil with a MSD Blaster SS to easily replace the electronic ignition module whenever it broke, instead of changing the whole coil + module. Actually saw a performance increase, cleaner spark plugs too.

Given I have to change pistons and heads, I've been thinking it may work great with:
-87mm slip-on piston set
-Empi 98-1325-B Cylinders heads. (close as possible to stock)

Afaik, ECU is able to handle any changes here (up to 1915cc), as long as valve train geometry is untouched.

My problem comes into choosing spark plugs: I'd need 12mm 3/4 reach.
I've used Bosch Super 4 and BP5ES in the past (the latter worked better), but stock head was 14mm 3/4.

Any suggestion into choosing:
-12mm 3/4 spark plugs
-A better cylinder head for an almost stock build and matching plugs.
-Some theory about choosing plugs will be highly appreciated too!!

Keep in mind that beside the fuel delivery, EFI engines are pretty much the same thing, don't refrain to comment if in doubt, any info may be helpful.
Also, I live in Central America, day temperature whole year are around 20ºC-32ºC (70ºF-90ºF). (rarely down to 16ºC when it's the coldest at night). I know it may have some saying in choosing spark plugs, but not sure just yet.

Thank you.

[Starbucket]

NGK 5829 also known as DP8EA-9

[67rustavenger]

Those EMPI heads as selected. Will cause the engine to feel sluggish.
A better choice would be Tim's Super Stock Heads. 37 x 32 valves.
https://www.performanceworkshop.net/cylinder-heads
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[Igpoe]

Heat range is backwards on NGK to what Bosch is. A 6 is warmer than an 8 and more suitable for a stock engine IMO

[azimech49]

[AutoMechanic]

I’ve been told by the beetle guys to only use Bosch Plugs in these cars. . That is what I have in mine and what I will be putting in it when I get it up and running again.

[Igpoe]

I initially used a #9 NGK, (very cold plug) and if I idled at a stop light for 10 seconds the plugs would foul and it would take a quarter mile to get cleared out again. I'm running an 1835 with about 8.3-1 compression. It accelerates and idles much better with the 6s.

[Starbucket]

[Igpoe]

I run points and condenser

[volksworld]