Flaked maize is quite tricky to work with but you know this already!
When I process flaked Maize I do it in small batches and I use powdered amylase. However, I have done the other method you're going to try.
The malt extracts are of no use for converting the starch from the maize but the malted Rye will be if it's already crushed.
The ratio I found worked ok was as follows. 1kg of Flaked Maize per 5 litres of water and 100g of crushed malted grains mixed with the Flaked Maize. You can scale up by simply multiplying these ratios
Heat the water to around 70oC and slowly add the Maize and malted grains stirring all the time. When all the Maize is in the mix will thicken but the enzymes in the malted grains will get to work much quicker this way. If you keep the pot on a heat you must keep the mash stirred constantly AND keep the temp around 65oC. After 15mins add another 100g of malted rye per kg of dry Flaked Maize used. Then cover and leave for about 30mins
Strain out all the grains from the converted wort, I found muslin cloth great for this, then rinse the grains with clean hot water and let it run into the wort.
I boil the wort for about 30 minutes to reduce it then cool as quickly as possible to pitching temp.
You could use so e of tHe malt extracts you have to get the wort to a gravity you want for fermenting.
Hope this helps
AM
