Switching Speaker Cabinets between a MARSHALL and a HIWATT!

I'm playing two killer halfstacks and I'm switching speaker cabinets between them so I'm playing the Marshall amp through the Hiwatt cab and the Hiwatt amp through the Marshall cab. Gear: 1976 Marshall JMP Super Lead 1976 Hiwatt DR103 1971 Marshall 1960B cab with '73 T1221 (close mic), '67 T1217, '71 T1281 and '68 T1221 1970 Marshall 1960B with 2X '73 Fane Crescendos 1973 Gibson Les Paul Custom Cherry with a '77 Super Distortion in the bridge. close mic: 548 room mic: C414 hallway nic: Beta57A Mic preamp: API3124+ Fryette Power Station 2