Then back to the original discussion.... If you only need wiring and some riv nuts to install the defender dash, then that should be all that's needed to install the Ministry of Defender Puma Dash.....If you have a riv nut setting tool, you can install a defender dash on a series 3 bulkhead. There maybe be a few holes that don’t line up but you can work through that. You’re also going to have to deal with the changes in the wiring and most likely convert to R380 transmission tunnel to clear your new transmission for LS swap.
I've searched all over for info on the MOD dash. I read somewhere that the airflow was about 30% higher than that of the stock heater fan. They suggest adding additional vents to the dash. This is going in a 109 pickup, so at least it doesn't have a large volume to cool. There's info on Series V8 swaps on expeditionlandrover.info that I've read and a few here and there that have done the LS swaps. The 109 is an R6, so it has the defender like bonet and the extra engine bay room. I've read where you can put Defender inner fenders on the series wings for more engine bay room. I'm sure I'll still have to move crossmembers and add engine mounts.The reason for the questions was to be sure what your plan was before spending the time to analyze you goals and provide accurate advice.
Years ago installed a Diava under dash AC setup from a 1994 NAS 90 into a LHD Serise III 109.
The AC worked great, but because the 109 had the under-powered 2.25, the AC made it that much slower.
The owner later had us install a GM 3.0 liter 4 cylinder engine conversion that had enough power to drive nicely and pull the AC compressor.
I am no expert on the Ministry of Defender Puma Dash replica, but will share with you what I know from talking to others.
The AC and heat both share the same pathway in the lower dash and this has a big impact on both the air flow and temperature.
The setup was designed and implemented in UK where it rarely gets hot and humid at the same time.
The number of outlet vents restricts the airflow making the benefits of the MOD dash marginal.
If it were mine, would want to talk to and see in person someone with an MOD operational dash.
Then if it suits your needs, by all means go with it.
If it won't suit your needs, then you can go with the early Defender Dash and install an under dash unit.
I am of the opinion that the Series III bulkhead is similar enough that it can be adapted accordingly.
Think you'll have to make some cuts for the heater and go with the suggestions Macker put up in post 6.
I would do your homework before deciding on an LS in a series.
The way I understand it, there are many many more changes required in a series than with a Defender.
While the vehicles look very similar they are different in nearly every way.
Best of luck.