Popshot & DannyC thanks for your comments - suggestions.
In no particular order.
438 x 20 rims [ listed as Dutch juvenile ] can't tyres or tubes being available for them - Only on the back apparently

front according to tyre is a 451
old school wood valve inner tubes - have allowed air in and maybe even holding it - we shall see
rim dynamo - removed may/may not work wiring getting in way and so tidied out of way
Magura hydraulic rim brake - works but may cause problems - see later
*
Front hub 2 x 6 with hub brake - correction Sachs orbit 2 x 6 - possibly faulty as it is either very hard to pedal or spins with no drive ? see later *
front ring 62T - way to high a gearing - see later *
box
lights - removed possibly don't work getting in way - untidy wiring etc
stand - used all the time else it falls over - my prototype does NOT !
more elastomer's than you can shake a stick at
2 handle bar positions - see later *
* Ok I suppose this is ' see later '
I first tried the bars below the seat , the cables seemed long enough for that , could not get going at all.
Decided that I was wasting my time chasing that as I knew I wanted the bars on the steering part and so move them up there , bit of a chore as you have to split the trike to do that and it is tricky to get back together if you are on your own.
The bars seem the wrong shape and not wide enough to be on the steering part , I fit them to try and make the brake levers be in the right place - failed miserably.
Bell and 2x changer hard up under thighs and bars not wide enough to get hands under and use brakes etc.
I added some straight bars in the under seat position and found I could not reach them either !
So we need to step away from this and re-group......
I did manage 14 ft but a huge struggle.
The main reason seems to be I have no low gears to pedal in ? see above Sachs 2 x 6.
So I can change out the 62T front ring for a MTB triple and put the chain on the 28T , that will help.
Changing the front wheel is not easy or quick ?
If a 406mm has the rim in a different place to the 451mm the Magura front brake may not have enough adjustment to meet the rim.
Also unless the 406mm comes with a hub brake and the above is true we will then have no brakes at all !
Yes I have a Nexus 7 with hub brake however that does not rate as ' quick ' as there is nother present to hold the brake reaction arm and the hub end changer may not fit in space available
The rear wheels are held on with M8 bolts ? which stops an easy swap out to SA hub brakes ?
So the handlebars I think I need to remove all the controls and start again , bit tricky as the Magura's are hydraulic and so not simply a matter or removing a cable.
So off to peruse some pictures to see how to do the bars and other useful stuff.
Sounds very much like mine , however my rear box is much smaller
Mine seems to build as per the paper trike plans , however they have no date on them 1995 was mentioned on another site so may be 26+ years old ?
all for now Paul