It will elongate if you pull it. Maybe splines are a bit tight.

While you have your distributor cap off, make sure your bobweight mechanism for ignition advance is free and working. If its seized or partially seized it will cost you horsepower.

Why did you need to fit HD shafts? Reason being my buddy snapped a rear shaft in a Puma 110 recently, but only moving off from standstill uphill. Not exactly a "tough" shaft..

I've fitted several V8's into Series over the years. The only differences I've seen with starters is the position of the solenoid. Range Rover/SD1 starters have the solenoid mounted to the side and MGB/Morgan V8's have the solenoid mounted below the starter, which can rub against the front prop...

A friend of mine used a US company called Vintage Air when he fitted A/C to a vintage car in the past. No harm sending them an e mail.

I've seen this mysterious starting behaviour before. The Landy concerned had two bad segments on the the starter's commutator. This means a lottery when going for a fresh start, as it depends on where the motor stopped rotating the last time it was used.

Gearbox to engine nuts are 9/16". The top two are either 9/16" or 5/8".

You could try giving Shielder Chassis a call. They're in Armagh. They might be able to assist.

I reckon you will miss the SU's once you fit the strombergs. They're a great carburettor.

I'd also vote for SU's if you're below 200bhp approx. They give lovely progression especially when off road and throttle sensitivity is important. The Webers don't like steep inclines or declines as the float mechanisms can lead to flooding or leaning out. What are your expectations on BHP?

I'm not sure if the Series 3 have them but my Series 2 has a threaded bolt in each pivot pin. From memory they are 1/4 UNF. I fitted two 90° grease nipples and give them a shot of EP140 gear oil from time to time. I use a small grease gun like those found in the tool kits of vintage cars.

Have a look at Robush.com

I've just finished putting an aftermarket bulkhead (Paddocks) onto an older aftermarket chassis (unknown) so all I had were original doors to assist in lining it all up. O/S needed 19mm of washers ahead of the outrigger and N/S needed only 5mm. These modern aftermarket parts must have zero...

Are you sure your voltage stabiliser casing is earthed properly? No earth, no function.

I have used sugar soap to soften paint in the past. Not sure if it's available anymore.