hi, I was looking into your post and this is what I'm about to do. My car is a rx8, I will be using the rx7 tranny and the b2600 housing but for what I have read so far the 87 b2600 housing should be a bolt on to the 4g63 block and the rx7 tranny  right? why do you need the adapter plate? Thank you and I will be looking forward for more updates on this built, btw I have been a mechanic for 1g and 2g for 15 years now so that is why I chose the 4g63 block.