HI Mark,
My first idea was to grind off the numbers, but, until now, no one wants to do it because is illegal.
The difference in the HP between the L26 (KP230) and L28E (N42 block and head), 135 and 170 respectively, is what made me think of doing the swap, but the necessity of using the L26 block is what 'd force me to overbore the block to 86... or at least to 85.5mm. Also, with the N42 head I could swap at anytime the whole EFI.
Ah, EFI. That would be good. You are familiar with this...megasquirt is a good setup.
To put the N42 head onto your L26 without overboring will produce a low compression engine, lower than stock. Even if you do overbore the L26, with the N42 head you'll still have a stock compression engine. You could use flat top pistons but they are not easy to find in this size off the shelf. This will raise compression but the N42 doesn't like high comprssion without work to the chambers. More and more cost for little gain. Keep your E88 and modify it to accept an efi manifold and injector notches. With an 2.5 mm overbore, you'll get nearly 2.8 capacity AND a higher compression! This engine, by your design, will make at least 170 and probably more if managed by megasquirt.
That L28 is better left complete and doesn't warrant pulling apart for part swapping. No advantage in my view. Work and develop your own engine and head.