1961/64 Falcon's came with either 144 or 170 I-6 engines. 200 I-6 introduced in Falcon's in 1965.
240 I-6 installed in 1965/74 F100/600's and 1965/71 Galaxie/LTD's, were not installed in any other Passenger Car.
In order to install a 240 in a Falcon, a HUGE hole would have to be cut in the firewall, as it's quite a bit longer than the 144/170/200 I-6's.
250 is another I-6, looks similar to 200's. Was first installed in 1969 Mustang/Fairlane/Torino/Comet.
All 144/170/200/250 I-6's have the intake manifold made as part of the cylinder head.
260 is a V8, introduced in 1962 Fairlane/Meteor, first Falcon's to come with it: 1963 1/2 Sprint hardtops and ragtops.
1961 was the first year for PCV, so no 1960 or earlier vehicle will have it.