Here is a video I came across on "You Tube" By ZS6DJM showing a conversion of a Yaesu FT-897 for 4m:
Making use of the large space in the radio.
PA unit and converter kit fitted inside the battery/PSU compartment.
Heat sink lies in front of the fans for cooling.
1w drive on 28Mhz gives 30w output on 70Mhz.