Hello Gil,
Here are two more photos of engine bay of 1966 1300 124 coupe model. One has a remote aircleaner located above the battery on the right side, avoiding conflict with fuel filler pipe, near the (single)carby.
As far as engines go, the following can be adapted to counterclockwise (left hand)rotation to suit the Standard Fiat 850 transaxle rotation, coupled via an Abarth bellhousing or a PBS bellhousing - be cautious, there are differences in which starter motors and clutch/flywheel diameters suit which bellhousing, and some opposite direction starters from the 60's are difficult to source :-
a) 1297cc 124A pushrod using two cam drive gears as per abarth original to reverse rotate cam relative to crank, and/or vice-versa b) same 124A overbored to 75.5mm for 1280cc as per original, if a source of pistons is found c) 1438cc 124B pushrod similarly reverse rotated d) 1585cc 131A pushrod which has a belt drive to cam, and this needs machine work to front of cam and front of crank to mount the reverse rotation camshaft drive gears from the 124A or B conversion, as well as use of the cam chain cover from the 124A or 124B to enclose the cam drive gears rather than the open arrangement of the 131A drive belt With this change the 131A is visually same as 124 A or B
I attach a sketch of the difference between the two types of camshafts 124A and 131A- the camlobe/tappet spacings and the cam journals/bearings sizes are identical in both types, but the relative location of the rear journal/bearing is 4mm different, showing they cannot be simply interchanged to obviate the machining of the noses of the 131A cam/cranks.
The standard 124A inlet /exhaust manifolds are mountable on the 124 B and the131A motor including the original 124A side draft carby or a larger one, or an Alquati pattern dual side draught manifold is also usable. An illustration of the latter is on this forum on Dave Robeys 1300OT Scorpione S , also shown in restorations section.
As mentioned elsewhere, close ratio 3rd and 4th gears are available for the standard Fiat 850 4 speed gearbox as is a small number of 9/35 ring and pinions (3.888 to 1)(without limited slip diff) for the same standard gearbox , both more suitable for the higher power motors. The original Abarth 1300 124 R and P was 3.9 to 1
Hope this helps
Cheers Trevor