If originals were unbalanced, why notSlenderchap said:Just make it unbalanced.... the original units are mostly unbalanced.
Almost all the parts are either "off the shelf" or can be substituted by off the shelf parts.
My biggest concern is the 2N3820 p-channel fet for which I don't have any equivalents and don't know a cheap european source for it.
I checked the parts required for this project more closely and it seems I have most of the parts already if I use BC560B instead of BC212B and BC550B instead of BC182B.
Probably in for 2 boards, unsure about cases, but considering them if wallet permits.