In the early 1980s I had numerous steel bikes including a Mercian.
I always regretted selling it. At some point migrated to carbon bikes but occasionally would look for a replacement for the Mercian.
But nothing ever came up, they were always the wrong size, wrong price or too beat up.
But a few months ago one came up on ebay and it seemed perfect, the right size in great shape at a reasonable although maybe slightly high price.
I knew this might be my only chance and pulled the trigger. But when I got it there where lingering questions:

Would it really fit me?
Would I like the ride like I remembered it?
Could I fit the parts on it that I wanted.

While I appreciate a vintage bike that is period correct, I am a firm believer that modern components are just better in terms or weight and performance.
I did not want to use down tube shifters and square taper bottom brackets. The first task was getting rear dropouts spread to 130mm which had a local frame shop do for me.
It turned out that the seatpost was extremely hard to get in so I got a flex hone and cleaned out the seat tube and now it is much better.
There was much thought about the crankset and was originally going to use Campy Over Torque, but after getting the BSA bottom bracket discovered it was not going to work,
so I went with Shimano 105 in sliver. Not the best fit visually, but the best I could do for my budget.
Here is what I have on the bike so far:

Innicycle headset
Shimano 105 crankset with Wheels Manufacturing BB
Ritchey Classic seatpost
SRAM Rival shifters
SRAM Force RD
Dia Compe Royal Compe brakes
Ritchey stem with black anodizing stripped and polished.
FSA bars with black anodizing stripped and polished.

I just ordered some Kinlin XR22T polished rims for the wheels.
In making measurements I discovered that the top tube is relatively short at 51cm, most of my bikes run 53 to 53.5cm.
But since my legs are relatively short I normally use a zero offset seatpost. So using a 25mm seatpost on this bike gets the fit close.
I was able to do a short test ride around the neighborhood by borrowing wheels and pedals from my other bike.
So far the I think it rides nice, very quiet and smooth. The SRAM shifting works perfectly.
I was surprised how stiff the frame feels, no noticeable flex, but that might become more apparent on a longer ride with some hills.
The weight is right around 19 lbs which what I had calcualted.
Really looking forward to doing a real ride on this.